import java.io.InputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.function.IntUnaryOperator;
import java.util.function.LongUnaryOperator;



public class Main {
    public static void main(String[] args) throws Exception {
        ExtendedScanner sc = new ExtendedScanner();
        FastPrintStream pw = new FastPrintStream();
        solve(sc, pw);
        sc.close();
        pw.flush();
        pw.close();
    }

    @SuppressWarnings("unchecked")
    public static void solve(ExtendedScanner sc, FastPrintStream pw) {
        int n = sc.nextInt();
        int m = sc.nextInt();
        Graph<SimpleEdge> g = new Graph<>(n);
        
        HashMap<Integer, Integer>[] ids = new HashMap[n];
        for (int i = 0; i < n; i++) {
            ids[i] = new HashMap<>();
        }
        SimpleEdge[] edges = new SimpleEdge[m];
        long[] ds = new long[m];
        for (int i = 0; i < m; i++) {
            int u = sc.nextInt() - 1;
            int v = sc.nextInt() - 1;
            long c = sc.nextLong();
            long d = sc.nextLong();
            SimpleEdge e = new SimpleEdge(u, v, c);
            g.addEdge(e);
            ids[u].put(v, i);
            ids[v].put(u, i);
            edges[i] = e;
            ds[i] = d;
        }

        Dijkstra<SimpleEdge> dij = new Dijkstra<>(g, 0);
        long s = dij.distance(n - 1);
        var path = dij.path(n - 1);
        Collections.sort(path, (e1, e2) -> toID(e1, ids) - toID(e2, ids));

        int k = path.size();
        int idx = 0;
        int id = toID(path.get(idx), ids);
        Graph<SimpleEdge> h = new Graph<>(n);
        for (int i = 0; i < m; i++) {
            if (i == id) {
                int u = edges[i].from, v = edges[i].to;
                h.addEdge(new SimpleEdge(u, v, ds[i]));
                if (++idx < k) {
                    id = toID(path.get(idx), ids);
                }
            } else {
                h.addEdge(edges[i]);
            }
        }

        long ans = s + new Dijkstra<>(h, n - 1).distance(0);
        pw.println(ans);
    }

    static int toID (SimpleEdge e, HashMap<Integer, Integer>[] ids) {
        return ids[e.from].get(e.to);
    }
}


/**
 * @author https://atcoder.jp/users/suisen
 */
class FastScanner implements AutoCloseable {
    private final ByteBuffer tokenBuf = new ByteBuffer();
    private final java.io.InputStream in;
    private final byte[] rawBuf = new byte[1 << 14];
    private int ptr = 0;
    private int buflen = 0;

    public FastScanner(java.io.InputStream in) {
        this.in = in;
    }

    public FastScanner() {
        this(new java.io.FileInputStream(java.io.FileDescriptor.in));
    }

    private final int readByte() {
        if (ptr < buflen) return rawBuf[ptr++];
        ptr = 0;
        try {
            buflen = in.read(rawBuf);
            if (buflen > 0) {
                return rawBuf[ptr++];
            } else {
                throw new java.io.EOFException();
            }
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    private final int readByteUnsafe() {
        if (ptr < buflen) return rawBuf[ptr++];
        ptr = 0;
        try {
            buflen = in.read(rawBuf);
            if (buflen > 0) {
                return rawBuf[ptr++];
            } else {
                return -1;
            }
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    private final int skipUnprintableChars() {
        int b = readByte();
        while (b <= 32 || b >= 127) b = readByte();
        return b;
    }

    private final void loadToken() {
        tokenBuf.clear();
        for (int b = skipUnprintableChars(); 32 < b && b < 127; b = readByteUnsafe()) {
            tokenBuf.append(b);
        }
    }

    public final boolean hasNext() {
        for (int b = readByteUnsafe(); b <= 32 || b >= 127; b = readByteUnsafe()) {
            if (b == -1) return false;
        }
        --ptr;
        return true;
    }

    public final String next() {
        loadToken();
        return new String(tokenBuf.getRawBuf(), 0, tokenBuf.size());
    }

    public final String nextLine() {
        tokenBuf.clear();
        for (int b = readByte(); b != '\n'; b = readByteUnsafe()) {
            if (b == -1) break;
            tokenBuf.append(b);
        }
        return new String(tokenBuf.getRawBuf(), 0, tokenBuf.size());
    }

    public final char nextChar() {
        return (char) skipUnprintableChars();
    }

    public final char[] nextChars() {
        loadToken();
        return tokenBuf.toCharArray();
    }

    public final long nextLong() {
        long n = 0;
        boolean isNegative = false;
        int b = skipUnprintableChars();
        if (b == '-') {
            isNegative = true;
            b = readByteUnsafe();
        }
        if (b < '0' || '9' < b) throw new NumberFormatException();
        while ('0' <= b && b <= '9') {
            // -9223372036854775808 - 9223372036854775807
            if (n >= 922337203685477580l) {
                if (n > 922337203685477580l) {
                    throw new ArithmeticException("long overflow");
                }
                if (isNegative) {
                    if (b >= '9') {
                        throw new ArithmeticException("long overflow");
                    }
                    n = -n - (b + '0');
                    b = readByteUnsafe();
                    if ('0' <= b && b <= '9') {
                        throw new ArithmeticException("long overflow");
                    } else if (b <= 32 || b >= 127) {
                        return n;
                    } else {
                        throw new NumberFormatException();
                    }
                } else {
                    if (b >= '8') {
                        throw new ArithmeticException("long overflow");
                    }
                    n = n * 10 + b - '0';
                    b = readByteUnsafe();
                    if ('0' <= b && b <= '9') {
                        throw new ArithmeticException("long overflow");
                    } else if (b <= 32 || b >= 127) {
                        return n;
                    } else {
                        throw new NumberFormatException();
                    }
                }
            }
            n = n * 10 + b - '0';
            b = readByteUnsafe();
        }
        if (b <= 32 || b >= 127) return isNegative ? -n : n;
        throw new NumberFormatException();
    }
    public final int nextInt() {
        long value = nextLong();
        if ((int) value != value) {
            throw new ArithmeticException("int overflow");
        }
        return (int) value;
    }
    public final double nextDouble() {
        return Double.parseDouble(next());
    }
    public final void close() {
        try {
            in.close();
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    private static final class ByteBuffer {
        private static final int DEFAULT_BUF_SIZE = 1 << 12;
        private byte[] buf;
        private int ptr = 0;
        private ByteBuffer(int capacity) {
            this.buf = new byte[capacity];
        }
        private ByteBuffer() {
            this(DEFAULT_BUF_SIZE);
        }
        private ByteBuffer append(int b) {
            if (ptr == buf.length) {
                int newLength = buf.length << 1;
                byte[] newBuf = new byte[newLength];
                System.arraycopy(buf, 0, newBuf, 0, buf.length);
                buf = newBuf;
            }
            buf[ptr++] = (byte) b;
            return this;
        }
        private char[] toCharArray() {
            char[] chs = new char[ptr];
            for (int i = 0; i < ptr; i++) {
                chs[i] = (char) buf[i];
            }
            return chs;
        }
        private byte[] getRawBuf() {
            return buf;
        }
        private int size() {
            return ptr;
        }
        private void clear() {
            ptr = 0;
        }
    }
}


/**
 * @author https://atcoder.jp/users/suisen
 */
final class ExtendedScanner extends FastScanner {
    public ExtendedScanner() {super();}
    public ExtendedScanner(InputStream in) {super(in);}
    public int[] ints(final int n) {
        final int[] a = new int[n];
        Arrays.setAll(a, $ -> nextInt());
        return a;
    }
    public int[] ints(final int n, final IntUnaryOperator f) {
        final int[] a = new int[n];
        Arrays.setAll(a, $ -> f.applyAsInt(nextInt()));
        return a;
    }
    public int[][] ints(final int n, final int m) {
        final int[][] a = new int[n][];
        Arrays.setAll(a, $ -> ints(m));
        return a;
    }
    public int[][] ints(final int n, final int m, final IntUnaryOperator f) {
        final int[][] a = new int[n][];
        Arrays.setAll(a, $ -> ints(m, f));
        return a;
    }
    public long[] longs(final int n) {
        final long[] a = new long[n];
        Arrays.setAll(a, $ -> nextLong());
        return a;
    }
    public long[] longs(final int n, final LongUnaryOperator f) {
        final long[] a = new long[n];
        Arrays.setAll(a, $ -> f.applyAsLong(nextLong()));
        return a;
    }
    public long[][] longs(final int n, final int m) {
        final long[][] a = new long[n][];
        Arrays.setAll(a, $ -> longs(m));
        return a;
    }
    public long[][] longs(final int n, final int m, final LongUnaryOperator f) {
        final long[][] a = new long[n][];
        Arrays.setAll(a, $ -> longs(m, f));
        return a;
    }
    public char[][] charArrays(final int n) {
        final char[][] c = new char[n][];
        Arrays.setAll(c, $ -> nextChars());
        return c;
    }
    public double[] doubles(final int n) {
        final double[] a = new double[n];
        Arrays.setAll(a, $ -> nextDouble());
        return a;
    }
    public double[][] doubles(final int n, final int m) {
        final double[][] a = new double[n][];
        Arrays.setAll(a, $ -> doubles(m));
        return a;
    }
    public String[] strings(final int n) {
        final String[] s = new String[n];
        Arrays.setAll(s, $ -> next());
        return s;
    }
}


/**
 * @verified
 * - https://judge.yosupo.jp/problem/shortest_path
 * 
 * @param <Edg> type of edge
 */
class Dijkstra<Edg extends AbstractEdge> {
    public static final long UNREACHABLE = Const.LINF;

    private static final class State implements Comparable<State> {
        final int v;
        final long d;
        State(int v, long d) {this.v = v; this.d = d;}
        public int compareTo(State s) {return d == s.d ? v - s.v : d > s.d ? 1 : -1;}
    }

    private final int n;
    private final int s;
    private final long[] dist;
    private final java.util.ArrayList<Edg> prev;

    public Dijkstra(AbstractGraph<Edg> g, int s) {
        this.n = g.getV();
        this.s = s;
        this.dist = new long[n];
        this.prev = new java.util.ArrayList<>(n);
        for (int i = 0; i < n; i++) {
            prev.add(null);
        }
        solve(g);
    }

    private void solve(AbstractGraph<Edg> g) {
        java.util.Arrays.fill(dist, UNREACHABLE);
        dist[s] = 0;
        java.util.PriorityQueue<State> pq = new java.util.PriorityQueue<>();
        pq.add(new State(s, 0l));
        while (pq.size() > 0) {
            State st = pq.poll();
            int u = st.v;
            if (st.d != dist[u]) continue;
            for (Edg e : g.getEdges(u)) {
                int v = e.to;
                long c = e.cost;
                if (e.cost < 0) throw new AssertionError("Negative cost.");
                if (dist[u] + c < dist[v]) {
                    dist[v] = dist[u] + c;
                    prev.set(v, e);
                    pq.add(new State(v, dist[v]));
                }
            }
        }
    }

    public java.util.ArrayList<Edg> path(int t) {
        if (dist[t] == UNREACHABLE) return null;
        java.util.ArrayList<Edg> path = new java.util.ArrayList<>();
        for (int v = t; v != s; v = prev.get(v).from) {
            path.add(prev.get(v));
        }
        int m = path.size();
        for (int l = 0, r = m - 1; l < r; l++, r--) {
            Edg tmp = path.get(l);
            path.set(l, path.get(r));
            path.set(r, tmp);
        }
        return path;
    }

    public long[] distances() {
        return dist;
    }

    public long distance(int i) {
        return dist[i];
    }

    public boolean isReachable(int t) {
        return dist[t] != UNREACHABLE;
    }
}

abstract class AbstractGraph<Edg extends AbstractEdge> {
    final int n;
    final java.util.ArrayList<Edg> edges;
    final java.util.ArrayList<java.util.ArrayList<Edg>> adj;
    public AbstractGraph(int n) {
        this.n = n;
        this.edges = new java.util.ArrayList<>(n);
        this.adj = new java.util.ArrayList<>(n);
        for (int i = 0; i < n; i++) {
            adj.add(new java.util.ArrayList<>());
        }
    }
    public abstract void addEdge(Edg edge);
    public Edg getEdge(int u, int i) {
        return adj.get(u).get(i);
    }
    public java.util.ArrayList<Edg> getEdges(int u) {
        return adj.get(u);
    }
    public java.util.ArrayList<Edg> getEdges() {
        return edges;
    }
    public int deg(int u) {
        return adj.get(u).size();
    }
    public int getV() {
        return n;
    }
    public int getE() {
        return edges.size();
    }
}

/**
 * @author https://atcoder.jp/users/suisen
 */
class FastPrintStream implements AutoCloseable {
    private static final int INT_MAX_LEN = 11;
    private static final int LONG_MAX_LEN = 20;

    private int precision = 9;

    private static final int BUF_SIZE = 1 << 14;
    private static final int BUF_SIZE_MINUS_INT_MAX_LEN = BUF_SIZE - INT_MAX_LEN;
    private static final int BUF_SIZE_MINUS_LONG_MAX_LEN = BUF_SIZE - LONG_MAX_LEN;
    private final byte[] buf = new byte[BUF_SIZE];
    private int ptr = 0;
    private final java.lang.reflect.Field strField;
    private final java.nio.charset.CharsetEncoder encoder;

    private final java.io.OutputStream out;

    public FastPrintStream(java.io.OutputStream out) {
        this.out = out;
        java.lang.reflect.Field f;
        try {
            f = java.lang.String.class.getDeclaredField("value");
            f.setAccessible(true);
        } catch (NoSuchFieldException | SecurityException e) {
            f = null;
        }
        this.strField = f;
        this.encoder = java.nio.charset.StandardCharsets.US_ASCII.newEncoder();
    }

    public FastPrintStream(java.io.File file) throws java.io.IOException {
        this(new java.io.FileOutputStream(file));
    }

    public FastPrintStream(java.lang.String filename) throws java.io.IOException {
        this(new java.io.File(filename));
    }

    public FastPrintStream() {
        this(new java.io.FileOutputStream(java.io.FileDescriptor.out));
    }

    public FastPrintStream println() {
        if (ptr == BUF_SIZE) internalFlush();
        buf[ptr++] = (byte) '\n';
        return this;
    }

    public FastPrintStream println(java.lang.Object o) {
        return print(o).println();
    }

    public FastPrintStream println(java.lang.String s) {
        return print(s).println();
    }

    public FastPrintStream println(char[] s) {
        return print(s).println();
    }

    public FastPrintStream println(char c) {
        return print(c).println();
    }

    public FastPrintStream println(int x) {
        return print(x).println();
    }

    public FastPrintStream println(long x) {
        return print(x).println();
    }

    public FastPrintStream println(double d, int precision) {
        return print(d, precision).println();
    }

    public FastPrintStream println(double d) {
        return print(d).println();
    }

    private FastPrintStream print(byte[] bytes) {
        int n = bytes.length;
        if (ptr + n > BUF_SIZE) {
            internalFlush();
            try {
                out.write(bytes);
            } catch (java.io.IOException e) {
                throw new java.io.UncheckedIOException(e);
            }
        } else {
            System.arraycopy(bytes, 0, buf, ptr, n);
            ptr += n;
        }
        return this;
    }

    public FastPrintStream print(java.lang.Object o) {
        return print(o.toString());
    }

    public FastPrintStream print(java.lang.String s) {
        if (strField == null) {
            return print(s.getBytes());
        } else {
            try {
                Object value = strField.get(s);
                if (value instanceof byte[]) {
                    return print((byte[]) value);
                } else {
                    return print((char[]) value);
                }
            } catch (IllegalAccessException e) {
                return print(s.getBytes());
            }
        }
    }

    public FastPrintStream print(char[] s) {
        try {
            return print(encoder.encode(java.nio.CharBuffer.wrap(s)).array());
        } catch (java.nio.charset.CharacterCodingException e) {
            byte[] bytes = new byte[s.length];
            for (int i = 0; i < s.length; i++) {
                bytes[i] = (byte) s[i];
            }
            return print(bytes);
        }
    }

    public FastPrintStream print(char c) {
        if (ptr == BUF_SIZE) internalFlush();
        buf[ptr++] = (byte) c;
        return this;
    }

    public FastPrintStream print(int x) {
        if (ptr > BUF_SIZE_MINUS_INT_MAX_LEN) internalFlush();
        if (-10 < x && x < 10) {
            if (x < 0) {
                buf[ptr++] = '-';
                x = -x;
            }
            buf[ptr++] = (byte) ('0' + x);
            return this;
        }
        int d;
        if (x < 0) {
            if (x == Integer.MIN_VALUE) {
                buf[ptr++] = '-'; buf[ptr++] = '2'; buf[ptr++] = '1'; buf[ptr++] = '4';
                buf[ptr++] = '7'; buf[ptr++] = '4'; buf[ptr++] = '8'; buf[ptr++] = '3';
                buf[ptr++] = '6'; buf[ptr++] = '4'; buf[ptr++] = '8';
                return this;
            }
            d = len(x = -x);
            buf[ptr++] = '-';
        } else {
            d = len(x);
        }
        int j = ptr += d; 
        while (x > 0) {
            buf[--j] = (byte) ('0' + (x % 10));
            x /= 10;
        }
        return this;
    }

    public FastPrintStream print(long x) {
        if ((int) x == x) return print((int) x);
        if (ptr > BUF_SIZE_MINUS_LONG_MAX_LEN) internalFlush();
        int d;
        if (x < 0) {
            if (x == Long.MIN_VALUE) {
                buf[ptr++] = '-'; buf[ptr++] = '9'; buf[ptr++] = '2'; buf[ptr++] = '2';
                buf[ptr++] = '3'; buf[ptr++] = '3'; buf[ptr++] = '7'; buf[ptr++] = '2';
                buf[ptr++] = '0'; buf[ptr++] = '3'; buf[ptr++] = '6'; buf[ptr++] = '8';
                buf[ptr++] = '5'; buf[ptr++] = '4'; buf[ptr++] = '7'; buf[ptr++] = '7';
                buf[ptr++] = '5'; buf[ptr++] = '8'; buf[ptr++] = '0'; buf[ptr++] = '8';
                return this;
            }
            d = len(x = -x);
            buf[ptr++] = '-';
        } else {
            d = len(x);
        }
        int j = ptr += d; 
        while (x > 0) {
            buf[--j] = (byte) ('0' + (x % 10));
            x /= 10;
        }
        return this;
    }

    public FastPrintStream print(double d, int precision) {
        if (d < 0) {
            print('-');
            d = -d;
        }
        d += Math.pow(10, -precision) / 2;
        print((long) d).print('.');
        d -= (long) d;
        for(int i = 0; i < precision; i++){
            d *= 10;
            print((int) d);
            d -= (int) d;
        }
        return this;
    }

    public FastPrintStream print(double d) {
        return print(d, precision);
    }

    public void setPrecision(int precision) {
        this.precision = precision;
    }

    private void internalFlush() {
        try {
            out.write(buf, 0, ptr);
            ptr = 0;
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    public void flush() {
        try {
            out.write(buf, 0, ptr);
            out.flush();
            ptr = 0;
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    public void close() {
        try {
            out.close();
        } catch (java.io.IOException e) {
            throw new java.io.UncheckedIOException(e);
        }
    }

    private static int len(int x) {
        return
            x >= 1000000000 ? 10 :
            x >= 100000000  ?  9 :
            x >= 10000000   ?  8 :
            x >= 1000000    ?  7 :
            x >= 100000     ?  6 :
            x >= 10000      ?  5 :
            x >= 1000       ?  4 :
            x >= 100        ?  3 :
            x >= 10         ?  2 : 1;
    }

    private static int len(long x) {
        return
            x >= 1000000000000000000l ? 19 :
            x >= 100000000000000000l  ? 18 :
            x >= 10000000000000000l   ? 17 :
            x >= 1000000000000000l    ? 16 :
            x >= 100000000000000l     ? 15 :
            x >= 10000000000000l      ? 14 :
            x >= 1000000000000l       ? 13 :
            x >= 100000000000l        ? 12 :
            x >= 10000000000l         ? 11 : 10;
    }
}

final class SimpleEdge extends AbstractEdge {
    public SimpleEdge(int from, int to, long cost) {
        super(from, to, cost);
    }
    public SimpleEdge(int from, int to) {
        super(from, to);
    }
    @Override
    public SimpleEdge reverse() {
        return new SimpleEdge(to, from, cost);
    }
}

abstract class AbstractEdge implements Comparable<AbstractEdge> {
    public final int from, to;
    public final long cost;
    public AbstractEdge(int from, int to, long cost) {
        this.from = from;
        this.to = to;
        this.cost = cost;
    }
    public AbstractEdge(int from, int to) {
        this(from, to, 1l);
    }
    public abstract AbstractEdge reverse();
    public int compareTo(AbstractEdge o) {
        return Long.compare(cost, o.cost);
    }
}
/**
 * @author https://atcoder.jp/users/suisen
 */
class Graph<Edg extends AbstractEdge> extends AbstractGraph<Edg> {
    public Graph(int n) {
        super(n);
    }
    @SuppressWarnings("unchecked")
    @Override
    public void addEdge(Edg edge) {
        Edg rev = (Edg) edge.reverse();
        adj.get(edge.from).add(edge);
        adj.get(edge.to).add(rev);
        edges.add(edge);
    }
}

class Const {
    public static final long   LINF   = 1l << 59;
    public static final int    IINF   = (1  << 30) - 1;
    public static final double DINF   = 1e150;
    
    public static final double SMALL  = 1e-12;
    public static final double MEDIUM = 1e-9;
    public static final double LARGE  = 1e-6;

    public static final long MOD1000000007 = 1000000007;
    public static final long MOD998244353  = 998244353 ;
    public static final long MOD754974721  = 754974721 ;
    public static final long MOD167772161  = 167772161 ;
    public static final long MOD469762049  = 469762049 ;

    public static final int[] dx8 = {1, 0, -1, 0, 1, -1, -1, 1};
    public static final int[] dy8 = {0, 1, 0, -1, 1, 1, -1, -1};
    public static final int[] dx4 = {1, 0, -1, 0};
    public static final int[] dy4 = {0, 1, 0, -1};
}