import java.io.*;
import java.math.BigInteger;
import java.util.*;

/**
 * Created by btk on 2017/03/16.
 */
public class Main {

    static FastScanner in;
    static PrintWriter out;

    static void solve() {
        int Gr = in.nextInt();
        int Gc = in.nextInt();
        int N = in.nextInt();
        int F = in.nextInt();
        int[] x=new int[N];
        int[] y=new int[N];
        int[] c=new int[N];
        for (int i = 0; i < N; i++) {
            x[i] = in.nextInt();
            y[i] = in.nextInt();
            c[i] = in.nextInt();
        }
        int[][] d=new int[212][212];
        for (int i = 0; i < 212; i++) {
            Arrays.fill(d[i],11234567);
        }
        d[0][0] = 0;
        for (int i = 0; i <= Gr; i++) {
            for (int j = 0; j <= Gc; j++) {
                for (int k = 0; k < N; k++) {
                    d[i+x[k]][j+y[k]] = Math.min(d[i+x[k]][j+y[k]],d[i][j]+c[k]);
                }
                d[i+1][j] = Math.min(d[i+1][j],d[i][j]+F);
                d[i][j+1] = Math.min(d[i][j+1],d[i][j]+F);
            }
        }
        out.println(d[Gr][Gc]);


    }
    public static void main(String[] args){
        in = new FastScanner();
        out = new PrintWriter(System.out);
        solve();
        out.flush();
        out.close();
    }
}

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;
    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        }else{
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }
    private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
    private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
    public boolean hasNext() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++; return hasNextByte();}
    public String next() {
        if (!hasNext()) throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while(isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    public long nextLong() {
        if (!hasNext()) throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while(true){
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            }else if(b == -1 || !isPrintableChar(b)){
                return minus ? -n : n;
            }else{
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }
    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) throw new NumberFormatException();
        return (int) nl;
    }
    public double nextDouble() { return Double.parseDouble(next());}
}
class Pair implements Comparable<Pair> {
    BigInteger a;
    int b;

    public Pair(BigInteger a, int b) {
        this.a = a;
        this.b = b;
    }

    //(a,b)が一致
    @Override
    public boolean equals(Object o) {
        if (o instanceof Pair) {
            Pair p = (Pair) o;
            return a == p.a && b == p.b;
        }
        return super.equals(o);
    }

    //辞書順比較
    @Override
    public int compareTo(Pair o) {
        if (!a.equals(o.a)) {
            return a.compareTo(o.a);
        }
        return Integer.compare(b,o.b);
    }
}