#include<iostream>#include<cstdio>#include<cstdlib>#include<cstring>#include<cmath>#include<vector>#include<set>#include<queue>#include<string>#include<algorithm>#define MAXSIZE 1000005#define LL long long#define INF 0x3f3f3f3fusing namespace std;//给出若干个建筑之间的一些路，每条路都有对应的长度和需要的花费，//问在保证源点1 到其他个点的距离最短的情况下，最少的花费是多少int n,m,vis[MAXSIZE],a[MAXSIZE],k,dist[MAXSIZE],id[MAXSIZE];struct node{    int u;    int v;    int w;    int c;    int next;}G[MAXSIZE];void Add(int u,int v,int w,int c){    G[k].u = u;    G[k].v = v;    G[k].w = w;    G[k].c = c;    G[k].next = a[u];    a[u] = k++;}int dij(){    memset(vis,0,sizeof(vis));    memset(id,-1,sizeof(id));    dist[1] = 0;    int minn ,p;    for(int i=1;i<k;i++)    {        minn = INF;        for(int j=1;j<=n;j++)        {            if(!vis[j] && dist[j] < minn)            {                minn = dist[j];                p = j;            }        }        if(minn == INF)            break;        vis[p] = 1;        for(int j=a[p];j!=-1;j=G[j].next)        {            int v = G[j].v;            if(dist[v] > dist[p] + G[j].w && !vis[v]) //距离更短就更新            {                dist[v] = dist[p] + G[j].w;                id[v] = j;            }                        //距离相同，花费更小就更新            else if(id[v]!=-1 && dist[v] == dist[p] + G[j].w && G[j].c < G[id[v]].c && !vis[v])            {                id[v] = j;            }        }    }    int sum=0;    for(int i=1;i<=n;i++)    {        if(id[i] == -1)            continue;        else            sum += G[id[i]].c;    }    return sum;}void Init(){    memset(a,-1,sizeof(a));    memset(vis,0,sizeof(vis));    for(int i=0;i<MAXSIZE;i++)        dist[i] = INF;    k = 1;}int main(){    int u,v,w,c;    while(scanf("%d%d",&n,&m),n+m)    {        Init();        for(int i=1;i<=m;i++)        {            scanf("%d%d%d%d",&u,&v,&w,&c);            Add(u,v,w,c);            Add(v,u,w,c);        }        int ans = dij();        printf("%d\n",ans);    }    return 0;}