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

#include <algorithm>

#include <cstdio>

#include <queue>

#include <cstring>

#define INF 0x3f3f3f



using namespace std;

const int MAX_V=100001;

struct node

{

    int to, dis, cost, next;

}edge[MAX_V];



int head[MAX_V], d[MAX_V], mcost[MAX_V];//mcoat一个?点??一条?

bool vis[MAX_V];

int n, m, cnt;



void add_edge(int u, int v, int d, int c)

{

    edge[cnt].to=v;

    edge[cnt].dis=d;

    edge[cnt].cost=c;

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

    head[u]=cnt++;

}



int spfa(int x)

{

    d[x]=0;         //必?！！！

    queue<int> que;

    que.push(x);

    vis[x]=true;

    while(!que.empty())

    {

        int u=que.front();

        que.pop();

        vis[u]=false;

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

        {

            node e = edge[i];

            if(d[e.to] > d[u]+e.dis)

            {

                mcost[e.to]=e.cost;     ////??最小花?

                d[e.to] = d[u]+e.dis;

                if(!vis[e.to])

                {

                    que.push(e.to);

                    vis[e.to]=true;

                }

            }

            else if(d[u]+e.dis==d[e.to] && e.cost<mcost[e.to])   ////??最小花?

                {

                    mcost[e.to]=e.cost;

                }

        }

    }

    int ans=0;

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

    {

     //   printf("\n%d\n", mcost[i]);

        ans+=mcost[i];

    }

    return ans;

}



int main()

{

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

    {

        cnt=0;          //从0?始！！！

        memset(head, -1, sizeof(head)); //初始化在前面！！！！

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

        {

            int u, v, d, c;

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

            add_edge(u,v,d,c);

            add_edge(v,u,d,c);      //双向的路！！！

        }



        //初始化

        memset(mcost, 0, sizeof(mcost));

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

        fill(vis, vis+n+1, false);



        int ans=spfa(1);

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

    }



    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.9304799035552604x):
    #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;  

    }