// Slower C++ solution:
#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);

    }

}

// Faster C++ solution for the same problem (measured speedup: 1.179373910201114x):
    #include <stdio.h>  

    #include <string.h>  

    #include <queue>  

    #include <iostream>  

    #include <algorithm>  

    using namespace std;  

    const int maxn=10050;  

    const int maxe=2005000;  

    const int INF=1e9;  

    struct note  

    {  

        int to;  

        int w;  

        int c;  

        int next;  

    };  

    note edge[maxe];  

    int head[maxn];  

    int ip;  

    void init()  

    {  

        memset(head,-1,sizeof(head));  

        ip=0;  

    }  

    void addedge(int u,int v,int w,int c)  

    {  

        edge[ip].to=v;  

        edge[ip].c=c;  

        edge[ip].w=w;  

        edge[ip].next=head[u];  

        head[u]=ip++;  

    }  

    int cost[maxn];  

    int dis[maxn];  

    bool vis[maxn];  

    queue<int>q;  

    void spfa(int s,int n)  

    {  

        while(!q.empty())q.pop();  

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

            cost[i]=dis[i]=INF;  

        memset(vis,false,sizeof(vis));  

        dis[s]=0;  

        cost[s]=0;  

        vis[s]=true;  

        q.push(s);  

        while(!q.empty())  

        {  

            int u=q.front();  

            q.pop();  

            vis[u]=false;  

            for(int i=head[u];i!=-1;i=edge[i].next)  

            {  

                int to=edge[i].to;  

                int val=edge[i].w;  

                if(dis[to]>dis[u]+val||(dis[to]==dis[u]+val&&cost[to]>edge[i].c))//有多条最短路?，取花?最小的  

                {  

                    dis[to]=dis[u]+val;  

                    cost[to]=edge[i].c;  

                    if(!vis[to])  

                    {  

                        q.push(to);  

                        vis[to]=true;  

                    }  

                }  

            }  

        }  

    }  

    int main()  

    {  

       // freopen("cin.txt","r",stdin);  

        int n,m;  

        int u,v,w,c;  

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

        {  

            if(n==0&&m==0) break;  

            init();  

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

            {  

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

                addedge(u,v,c,w);  

                addedge(v,u,c,w);  

            }  

            spfa(1,n);  

            int ans=0;  

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

                ans+=cost[i];  

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

        }  

        return 0;  

    }