/**
 *  date : 2020-11-27 22:44:21
 */

#pragma region kyopro_template
#define Nyaan_template
#include <immintrin.h>
#include <bits/stdc++.h>
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define each(x, v) for (auto &x : v)
#define all(v) (v).begin(), (v).end()
#define sz(v) ((int)(v).size())
#define mem(a, val) memset(a, val, sizeof(a))
#define ini(...)   \
  int __VA_ARGS__; \
  in(__VA_ARGS__)
#define inl(...)         \
  long long __VA_ARGS__; \
  in(__VA_ARGS__)
#define ins(...)      \
  string __VA_ARGS__; \
  in(__VA_ARGS__)
#define inc(...)    \
  char __VA_ARGS__; \
  in(__VA_ARGS__)
#define in2(s, t)                           \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i]);                         \
  }
#define in3(s, t, u)                        \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i], u[i]);                   \
  }
#define in4(s, t, u, v)                     \
  for (int i = 0; i < (int)s.size(); i++) { \
    in(s[i], t[i], u[i], v[i]);             \
  }
#define rep(i, N) for (long long i = 0; i < (long long)(N); i++)
#define repr(i, N) for (long long i = (long long)(N)-1; i >= 0; i--)
#define rep1(i, N) for (long long i = 1; i <= (long long)(N); i++)
#define repr1(i, N) for (long long i = (N); (long long)(i) > 0; i--)
#define reg(i, a, b) for (long long i = (a); i < (b); i++)
#define die(...)      \
  do {                \
    out(__VA_ARGS__); \
    return;           \
  } while (0)
using namespace std;
using ll = long long;
template <class T>
using V = vector<T>;
using vi = vector<int>;
using vl = vector<long long>;
using vvi = vector<vector<int>>;
using vd = V<double>;
using vs = V<string>;
using vvl = vector<vector<long long>>;
using P = pair<long long, long long>;
using vp = vector<P>;
using pii = pair<int, int>;
using vpi = vector<pair<int, int>>;
constexpr int inf = 1001001001;
constexpr long long infLL = (1LL << 61) - 1;
template <typename T, typename U>
inline bool amin(T &x, U y) {
  return (y < x) ? (x = y, true) : false;
}
template <typename T, typename U>
inline bool amax(T &x, U y) {
  return (x < y) ? (x = y, true) : false;
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
  os << p.first << " " << p.second;
  return os;
}
template <typename T, typename U>
istream &operator>>(istream &is, pair<T, U> &p) {
  is >> p.first >> p.second;
  return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  int s = (int)v.size();
  for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i];
  return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
  for (auto &x : v) is >> x;
  return is;
}
void in() {}
template <typename T, class... U>
void in(T &t, U &... u) {
  cin >> t;
  in(u...);
}
void out() { cout << "\n"; }
template <typename T, class... U>
void out(const T &t, const U &... u) {
  cout << t;
  if (sizeof...(u)) cout << " ";
  out(u...);
}

#ifdef NyaanDebug
#define trc(...)                   \
  do {                             \
    cerr << #__VA_ARGS__ << " = "; \
    dbg_out(__VA_ARGS__);          \
  } while (0)
#define trca(v, N)       \
  do {                   \
    cerr << #v << " = "; \
    array_out(v, N);     \
  } while (0)
#define trcc(v)                             \
  do {                                      \
    cerr << #v << " = {";                   \
    each(x, v) { cerr << " " << x << ","; } \
    cerr << "}" << endl;                    \
  } while (0)
template <typename T>
void _cout(const T &c) {
  cerr << c;
}
void _cout(const int &c) {
  if (c == 1001001001)
    cerr << "inf";
  else if (c == -1001001001)
    cerr << "-inf";
  else
    cerr << c;
}
void _cout(const unsigned int &c) {
  if (c == 1001001001)
    cerr << "inf";
  else
    cerr << c;
}
void _cout(const long long &c) {
  if (c == 1001001001 || c == (1LL << 61) - 1)
    cerr << "inf";
  else if (c == -1001001001 || c == -((1LL << 61) - 1))
    cerr << "-inf";
  else
    cerr << c;
}
void _cout(const unsigned long long &c) {
  if (c == 1001001001 || c == (1LL << 61) - 1)
    cerr << "inf";
  else
    cerr << c;
}
template <typename T, typename U>
void _cout(const pair<T, U> &p) {
  cerr << "{ ";
  _cout(p.fi);
  cerr << ", ";
  _cout(p.se);
  cerr << " } ";
}
template <typename T>
void _cout(const vector<T> &v) {
  int s = v.size();
  cerr << "{ ";
  for (int i = 0; i < s; i++) {
    cerr << (i ? ", " : "");
    _cout(v[i]);
  }
  cerr << " } ";
}
template <typename T>
void _cout(const vector<vector<T>> &v) {
  cerr << "[ ";
  for (const auto &x : v) {
    cerr << endl;
    _cout(x);
    cerr << ", ";
  }
  cerr << endl << " ] ";
}
void dbg_out() { cerr << endl; }
template <typename T, class... U>
void dbg_out(const T &t, const U &... u) {
  _cout(t);
  if (sizeof...(u)) cerr << ", ";
  dbg_out(u...);
}
template <typename T>
void array_out(const T &v, int s) {
  cerr << "{ ";
  for (int i = 0; i < s; i++) {
    cerr << (i ? ", " : "");
    _cout(v[i]);
  }
  cerr << " } " << endl;
}
template <typename T>
void array_out(const T &v, int H, int W) {
  cerr << "[ ";
  for (int i = 0; i < H; i++) {
    cerr << (i ? ", " : "");
    array_out(v[i], W);
  }
  cerr << " ] " << endl;
}
#else
#define trc(...)
#define trca(...)
#define trcc(...)
#endif

inline int popcnt(unsigned long long a) { return __builtin_popcountll(a); }
inline int lsb(unsigned long long a) { return __builtin_ctzll(a); }
inline int msb(unsigned long long a) { return 63 - __builtin_clzll(a); }
template <typename T>
inline int getbit(T a, int i) {
  return (a >> i) & 1;
}
template <typename T>
inline void setbit(T &a, int i) {
  a |= (1LL << i);
}
template <typename T>
inline void delbit(T &a, int i) {
  a &= ~(1LL << i);
}
template <typename T>
int lb(const vector<T> &v, const T &a) {
  return lower_bound(begin(v), end(v), a) - begin(v);
}
template <typename T>
int ub(const vector<T> &v, const T &a) {
  return upper_bound(begin(v), end(v), a) - begin(v);
}
template <typename T>
int btw(T a, T x, T b) {
  return a <= x && x < b;
}
template <typename T, typename U>
T ceil(T a, U b) {
  return (a + b - 1) / b;
}
constexpr long long TEN(int n) {
  long long ret = 1, x = 10;
  while (n) {
    if (n & 1) ret *= x;
    x *= x;
    n >>= 1;
  }
  return ret;
}
template <typename T>
vector<T> mkrui(const vector<T> &v) {
  vector<T> ret(v.size() + 1);
  for (int i = 0; i < int(v.size()); i++) ret[i + 1] = ret[i] + v[i];
  return ret;
};
template <typename T>
vector<T> mkuni(const vector<T> &v) {
  vector<T> ret(v);
  sort(ret.begin(), ret.end());
  ret.erase(unique(ret.begin(), ret.end()), ret.end());
  return ret;
}
template <typename F>
vector<int> mkord(int N, F f) {
  vector<int> ord(N);
  iota(begin(ord), end(ord), 0);
  sort(begin(ord), end(ord), f);
  return ord;
}
template <typename T = int>
vector<T> mkiota(int N) {
  vector<T> ret(N);
  iota(begin(ret), end(ret), 0);
  return ret;
}
template <typename T>
vector<int> mkinv(vector<T> &v) {
  vector<int> inv(v.size());
  for (int i = 0; i < (int)v.size(); i++) inv[v[i]] = i;
  return inv;
}

struct IoSetupNya {
  IoSetupNya() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(15);
    cerr << fixed << setprecision(7);
  }
} iosetupnya;

void solve();
int main() { solve(); }

#pragma endregion
using namespace std;

using namespace std;

template <typename Key, typename Val>
struct RadixHeap {
  using uint = typename make_unsigned<Key>::type;
  static constexpr int bit = sizeof(Key) * 8;
  array<vector<pair<uint, Val> >, bit + 1> vs;
  array<uint, bit + 1> ms;

  int s;
  uint last;

  RadixHeap() : s(0), last(0) { fill(begin(ms), end(ms), uint(-1)); }

  bool empty() const { return s == 0; }

  int size() const { return s; }

  __attribute__((target("lzcnt"))) inline uint64_t getbit(uint a) const {
    return 64 - _lzcnt_u64(a);
  }

  void push(const uint &key, const Val &val) {
    s++;
    uint64_t b = getbit(key ^ last);
    vs[b].emplace_back(key, val);
    ms[b] = min(key, ms[b]);
  }

  pair<uint, Val> pop() {
    if (ms[0] == uint(-1)) {
      int idx = 1;
      while (ms[idx] == uint(-1)) idx++;
      last = ms[idx];
      for (auto &p : vs[idx]) {
        uint64_t b = getbit(p.first ^ last);
        vs[b].emplace_back(p);
        ms[b] = min(p.first, ms[b]);
      }
      vs[idx].clear();
      ms[idx] = uint(-1);
    }
    --s;
    auto res = vs[0].back();
    vs[0].pop_back();
    if (vs[0].empty()) ms[0] = uint(-1);
    return res;
  }
};

/**
 * @brief Radix Heap
 * @docs docs/data-structure/radix-heap.md
 */
using namespace std;

template <typename T>
struct edge {
  int src, to;
  T cost;

  edge(int _to, T _cost) : src(-1), to(_to), cost(_cost) {}
  edge(int _src, int _to, T _cost) : src(_src), to(_to), cost(_cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator int() const { return to; }
};
template <typename T>
using Edges = vector<edge<T>>;
template <typename T>
using WeightedGraph = vector<Edges<T>>;
using UnweightedGraph = vector<vector<int>>;

// Input of (Unweighted) Graph
UnweightedGraph graph(int N, int M = -1, bool is_directed = false,
                      bool is_1origin = true) {
  UnweightedGraph g(N);
  if (M == -1) M = N - 1;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    if (is_1origin) x--, y--;
    g[x].push_back(y);
    if (!is_directed) g[y].push_back(x);
  }
  return g;
}

// Input of Weighted Graph
template <typename T>
WeightedGraph<T> wgraph(int N, int M = -1, bool is_directed = false,
                        bool is_1origin = true) {
  WeightedGraph<T> g(N);
  if (M == -1) M = N - 1;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    cin >> c;
    if (is_1origin) x--, y--;
    g[x].eb(x, y, c);
    if (!is_directed) g[y].eb(y, x, c);
  }
  return g;
}

// Input of Edges
template <typename T>
Edges<T> esgraph(int N, int M, int is_weighted = true, bool is_1origin = true) {
  Edges<T> es;
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    if (is_weighted)
      cin >> c;
    else
      c = 1;
    if (is_1origin) x--, y--;
    es.emplace_back(x, y, c);
  }
  return es;
}

// Input of Adjacency Matrix
template <typename T>
vector<vector<T>> adjgraph(int N, int M, T INF, int is_weighted = true,
                           bool is_directed = false, bool is_1origin = true) {
  vector<vector<T>> d(N, vector<T>(N, INF));
  for (int _ = 0; _ < M; _++) {
    int x, y;
    cin >> x >> y;
    T c;
    if (is_weighted)
      cin >> c;
    else
      c = 1;
    if (is_1origin) x--, y--;
    d[x][y] = c;
    if (!is_directed) d[y][x] = c;
  }
  return d;
}
// unreachable -> {-1, -1}
template <typename T>
vector<pair<T, int>> dijkstra_restore(WeightedGraph<T> &g, int start = 0) {
  int N = (int)g.size();
  using P = pair<T, int>;
  vector<P> d(N, P{-1, -1});
  RadixHeap<T, int> Q;
  d[start].first = 0;
  Q.push(0, start);
  while (!Q.empty()) {
    auto p = Q.pop();
    int cur = p.second;
    T dc = d[cur].first;
    if (dc < T(p.first)) continue;
    for (auto dst : g[cur]) {
      if (d[dst].first == T(-1) || dc + dst.cost < d[dst].first) {
        d[dst] = P{dc + dst.cost, cur};
        Q.push(dc + dst.cost, dst);
      }
    }
  }
  return d;
}

/*
 * @brief ダイクストラ法(復元付き)
 * @docs docs/shortest-path/dijkstra-with-restore.md
 **/


void solve() {
  ini(N, M);
  WeightedGraph<ll> g(N);
  map<P, P> m;
  rep(i, M) {
    ini(u, v, c, d);
    --u, --v;
    m[P(u, v)] = m[P(v, u)] = P(c, d);
    g[u].emplace_back(v, c);
    g[v].emplace_back(u, c);
  }
  auto d = dijkstra_restore(g);

  ll ans = d[N - 1].first;

  for (int v = N - 1; v != 0;) {
    int u = d[v].second;
    ll nc = m[P(u, v)].second;
    m[P(u, v)].first = m[P(v, u)].first = nc;
    v = u;
  }

  rep(u, N) each(e, g[u]) { e.cost = m[P(u, e)].first; }

  auto d2 = dijkstra_restore(g);
  out(ans + d2.back().first);
}