// Slower C++ solution:
#include <queue>

#include <vector>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <iostream>

#include <algorithm>

const int INF=0x3f3f3f3f;

using namespace std;

struct edge{

    int to,cost,w;

};

int V,d[10005],dis[10005];

vector<edge> G[20005];

typedef pair<int,int> P;

void dijkstra(int s){

    int i,v;

	priority_queue<P,vector<P>,greater<P> >que;

	fill(d,d+V+1,INF);

	fill(dis,dis+V+1,INF);

	d[s]=dis[s]=0;

	que.push(P(0,s));

	while(!que.empty()){

		P p=que.top(); que.pop();

		v=p.second;

		if(d[v]<p.first)

        continue;

		for(i=0;i<G[v].size();i++){

			edge e=G[v][i];

			if(d[e.to]>d[v]+e.cost){

				d[e.to]=d[v]+e.cost;

                dis[e.to]=e.w;

				que.push(P(d[e.to],e.to));

			}

			else if(d[e.to]==d[v]+e.cost)

            dis[e.to]=min(dis[e.to],e.w);

		}

	}

}

int main(){

    int m,st,en,i,j,x,y,z,q,ans;

    edge temp;

    while(scanf("%d%d",&V,&m)!=EOF&&(V||m)){

        for(i=0;i<=V;i++)

        G[i].clear();

        for(i=0;i<m;i++){

            scanf("%d%d%d%d",&x,&y,&z,&q);

            temp.to=y;temp.cost=z;temp.w=q;

            G[x].push_back(temp);

            temp.to=x;

            G[y].push_back(temp);

        }

        dijkstra(1);

        ans=0;

        for(i=1;i<=V;i++)

        ans+=dis[i];

        printf("%d\n",ans);

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1945899153710673x):
#include <iostream>

#include <cstdio>

#include <cstring>

#include <vector>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

const int MAXN = 10005;

struct Edge

{

    int to, w, cost;

    Edge() {}

    Edge(int a, int b, int c): to(a), w(b), cost(c) {}

    bool operator < (const Edge &r) const

    {

        return w > r.w || w == r.w && cost > r.cost;

    }

};

vector<Edge> G[MAXN];

bool vis[MAXN];

int dist[MAXN];

int cost[MAXN];

int pre[MAXN];

void Dijkstra(int n, int start)

{

    for (int i = 0; i <= n; i++)

        vis[i] = 0, dist[i] = cost[i] = INF;

    priority_queue<Edge> que;

    que.push(Edge(start, 0, 0));

    dist[start] = cost[start] = 0;

    pre[start] = start;

    Edge tmp;

    while (!que.empty())

    {

        tmp = que.top();

        que.pop();

        int u = tmp.to;

    //    cout << tmp.to << endl;

        if (vis[u]) continue;

        vis[u] = 1;

        for (int i = 0; i < G[u].size(); i++)

        {

            int v = G[u][i].to;

            int w = G[u][i].w;

    //        cout << v << " " << w << " " << G[u][i].cost << endl;

    //        cout << dist[v] << " " << cost[v] << endl;

     //       cout << dist[u] << " " << cost[u] << endl;

            if (!vis[v] && dist[v] > dist[u] + w)

            {

                dist[v] = dist[u] + w;

                cost[v] = G[u][i].cost;

      //          cout <<"s1  " << v << " " << dist[v] << " " << cost[v] << endl;

                pre[v] = u;

                que.push(Edge(v, dist[v], cost[v]));

            }

            else if (!vis[v] && dist[v] == dist[u]+w && cost[v] >  G[u][i].cost)

            {

                cost[v] = G[u][i].cost;

         //       cout << "s2  " <<  v << " " << dist[v] << " " << cost[v] << endl;

                pre[v] = u;

                que.push(Edge(v, dist[v], cost[v]));

            }

        }

    }

   // for (int i = 2; i <= n; i++) cout << cost[i] - cost[pre[i]] <<endl;

}

int n, m;

int main()

{

    while (~scanf("%d%d", &n, &m) && (n+m))

    {

        for (int i = 1; i <= n; i++)

            G[i].clear();

        for (int i = 1; i <= m; i++)

        {

            int u, v, d, c; scanf("%d%d%d%d", &u, &v, &d, &c);

            G[u].push_back(Edge(v, d, c));

            G[v].push_back(Edge(u, d, c));

        }

        Dijkstra(n, 1);

        int ans = 0;

        for (int i = 2; i <= n; i++) ans += cost[i];

        printf("%d\n", ans);

    }

}