#line 1 "main.cpp"

/**
 * @title Template
 */

#include <iostream>
#include <algorithm>
#include <utility>
#include <numeric>
#include <vector>
#include <array>
#include <cassert>
#include <queue>

#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/chmin_chmax.cpp"

template <class T, class U>
constexpr bool chmin(T &lhs, const U &rhs) {
  if (lhs > rhs) { lhs = rhs; return true; }
  return false;
}

template <class T, class U>
constexpr bool chmax(T &lhs, const U &rhs) {
  if (lhs < rhs) { lhs = rhs; return true; }
  return false;
}

/**
 * @title Chmin/Chmax
 */
#line 2 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

#line 4 "/Users/kodamankod/Desktop/cpp_programming/Library/other/range.cpp"

class range {
  struct iter {
    std::size_t itr;
    constexpr iter(std::size_t pos) noexcept: itr(pos) { }
    constexpr void operator ++ () noexcept { ++itr; }
    constexpr bool operator != (iter other) const noexcept { return itr != other.itr; }
    constexpr std::size_t operator * () const noexcept { return itr; }
  };

  struct reviter {
    std::size_t itr;
    constexpr reviter(std::size_t pos) noexcept: itr(pos) { }
    constexpr void operator ++ () noexcept { --itr; }
    constexpr bool operator != (reviter other) const noexcept { return itr != other.itr; }
    constexpr std::size_t operator * () const noexcept { return itr; }
  };

  const iter first, last;

public:
  constexpr range(std::size_t first, std::size_t last) noexcept: first(first), last(std::max(first, last)) { }
  constexpr iter begin() const noexcept { return first; }
  constexpr iter end() const noexcept { return last; }
  constexpr reviter rbegin() const noexcept { return reviter(*last - 1); } 
  constexpr reviter rend() const noexcept { return reviter(*first - 1); } 
};

/**
 * @title Range
 */
#line 17 "main.cpp"

using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

constexpr i32 inf32 = (i32(1) << 30) - 1;
constexpr i64 inf64 = (i64(1) << 62) - 1;

int main() {
  usize N, M;
  std::cin >> N >> M;
  std::vector<usize> U(M), V(M);
  std::vector<u64> C(M), D(M);
  std::vector<std::vector<std::pair<usize, usize>>> graph(N);
  for (auto i: range(0, M)) {
    std::cin >> U[i] >> V[i] >> C[i] >> D[i];
    U[i] -= 1; V[i] -= 1;
    graph[U[i]].emplace_back(V[i], i);
    graph[V[i]].emplace_back(U[i], i);
  }
  const auto solve = [&](const usize src, const usize dest) {
    std::vector<u64> dist(N, inf64);
    std::vector<usize> last(N, M);
    std::priority_queue<std::pair<u64, usize>, std::vector<std::pair<u64, usize>>, std::greater<std::pair<u64, usize>>> que;
    const auto try_push = [&](const usize u, const usize e, const usize d) {
      if (chmin(dist[u], d)) {
        last[u] = e;
        que.emplace(dist[u], u);
      }
    };
    try_push(src, M, 0);
    while (!que.empty()) {
      const auto [d, u] = que.top();
      que.pop();
      if (dist[u] < d) {
        continue;
      }
      for (const auto [v, e]: graph[u]) {
        try_push(v, e, d + C[e]);
      }
    }
    usize cur = dest;
    while (last[cur] != M) {
      const auto i = last[cur];
      cur = (U[i] == cur ? V[i] : U[i]);
      std::swap(C[i], D[i]);
    }
    return dist[dest];
  };
  u64 ans = 0;
  ans += solve(0, N - 1);
  ans += solve(N - 1, 0);
  std::cout << ans << '\n';
  return 0;
}