#include <bits/stdc++.h>
using namespace std;
#define int long long
#define stoi stoll
using ll=long long;
using vi=vector<int>;
using pii=pair<int,int>;
#define ALL(c) begin(c),end(c)
#define RALL(c) rbegin(c),rend(c)
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define FORE(x,c) for(auto &&x:c)
#define REPF(i,a,n) for(int i=a,i##len=(int)(n);i<i##len;++i)
#define REP(i,n) REPF(i,0,n)
#define REPR(i,n) for(int i=(int)(n);i>=0;--i)
#define SZ(c) ((int)c.size())
#define CONTAIN(c,x) (c.find(x)!=end(c))
#define INSEG(l,x,r) ((l)<=(x)&&(x)<(r))
#define dump(...)
#define pb push_back
#define _ 0
const signed INF_=1001001001; const long long INF=1001001001001001001LL;
const int DX[9]={0,1,0,-1,1,1,-1,-1,0},DY[9]={-1,0,1,0,-1,1,1,-1,0};
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v))os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T, class U> bool chmax(T &a,const U &b){return a<b?a=b,1:0;}
template<class T, class U> bool chmin(T &a,const U &b){return a>b?a=b,1:0;}
template <class T> void PSUM(T& c) {partial_sum(begin(c), end(c), begin(c));}
template<class T> using heap=priority_queue<T,vector<T>,greater<T>>;
struct before_main_function {
    before_main_function() {
        cin.tie(0); ios::sync_with_stdio(false);
        cout << setprecision(15) << fixed;
        // #define endl "\n"
    }
} before_main_function;
//------------------8<------------------------------------8<--------------------

signed main() {
    while (1) {
        int n, m;
        cin >> n >> m;
        if (n == 0 && m == 0) {
            break;
        }

        int ans = 0;
        vector<vector<vector<int>>> g(n);
        vector<vector<int>> edge(m);
        REP(i, m) {
            int a, b, c, d;
            cin >> a >> b >> c >> d;
            a--, b--;
            g[a].push_back({b, c, d});
            g[b].push_back({a, c, d});
            edge[i] = {a, b, c, d};
            ans += d;
        }

        heap<pii> hp;
        vector<int> dist(n, INF);
        dist[0] = 0;
        hp.push({0, 0});
        while (!hp.empty()) {
            int v = hp.top().second; hp.pop();
            FORE(e, g[v]) {
                int w = e[0];
                if (dist[w] > dist[v] + e[1]) {
                    dist[w] = dist[v] + e[1];
                    hp.push({dist[w], w});
                }
            }
        }
        
        vector<vector<int>> from_cost(n);
        REP(i, m) {
            int a = edge[i][0];
            int b = edge[i][1];
            int c = edge[i][2];
            int d = edge[i][3];
            if (dist[a] > dist[b]) swap(a, b);
            if (dist[a] + c == dist[b]) {
                from_cost[b].push_back(d);
            } else {
                ans -= d;
            }
        }

        REP(i, n) {
            sort(ALL(from_cost[i]));
            REPF(j, 1, SZ(from_cost[i])) ans -= from_cost[i][j];
        }
        
        cout << ans << endl;
    }
    return (0^_^0);
}




Measured memory_bytes: 7560