#include <iostream>
#include <vector>
#include <queue>
using namespace std;
using ll = long long;

struct P{
    int to;
    ll cost;
    int i;
    P(ll cost, int to, int i): to(to), i(i), cost(cost){}
    bool operator>(const P &other) const {
        return this->cost > other.cost;
    }
};

bool chmin(ll &a, ll x){
    if(a > x){
        a = x;
        return true;
    }else return false;
}

int main(){
    int n, m;
    cin >> n >> m;
    vector<int> u(m), v(m), c(m), d(m);
    for(int i = 0; i < m; i++){
        cin >> u[i] >> v[i] >> c[i] >> d[i];
        u[i]--; v[i]--;
    }

    ll ans = 0;
    vector<bool> isused(m, false);
    for(int turn = 0; turn < 2; turn++){
        vector<vector<P>> G(n);
        for(int i = 0; i < m; i++){
            if(isused[i]) c[i] = d[i];
            G[u[i]].emplace_back(c[i], v[i], i);
            G[v[i]].emplace_back(c[i], u[i], i);
        }

        vector<ll> cost(n, 1LL << 60);
        vector<P> prev(n, P{-1, -1, -1});
        cost[0] = 0;
        priority_queue<P, vector<P>, greater<P>> Q;
        Q.emplace(0, 0, 0);
        while(!Q.empty()){
            auto c = Q.top(); Q.pop();
            if(cost[c.to] < c.cost) continue;

            for(auto &nex: G[c.to]){
                if(chmin(cost[nex.to], cost[c.to]+nex.cost)){
                    prev[nex.to].to = c.to;
                    prev[nex.to].i = nex.i;
                    Q.emplace(cost[nex.to], nex.to, nex.i);
                }
            }
        }

        ans += cost[n-1];
        
        int cur = n-1;
        while(prev[cur].i != -1){
            isused[prev[cur].i] = true;
            cur = prev[cur].to;
        }
    }

    cout << ans << endl;
    return 0;
}