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

#include<cstdio>

#include<cstdlib>

#include<string>

#include<cstring>

#include<algorithm>

#include<queue>

#include<vector>

#define N 20100

#define M 50010

#define rg register

using namespace std;

typedef long long ll;

typedef double db;

int n,m,tot=0;

int dis[N],head[N],vis[N];

int nxt[M],to[M],w[M],c[M];

void link(int x,int y,int z,int v){

	nxt[tot]=head[x],to[tot]=y,w[tot]=z,c[tot]=v,head[x]=tot++;

}

void spfa(){

	queue <int> q;

	memset(dis,0x3f,sizeof(dis));

	memset(vis,0,sizeof(vis));

	q.push(1),dis[1]=0,vis[1]=1;

	while (!q.empty()){

		int x=q.front();q.pop();

		for (int i=head[x];i!=-1;i=nxt[i]){

			int v=to[i];

			if (dis[v]<=dis[x]+w[i]) continue;

			dis[v]=dis[x]+w[i];

			if (!vis[v]) vis[v]=1,q.push(v);

		}

		vis[x]=0;

	}

}

int main(){

//	freopen ("2249.in","r",stdin);

//	freopen ("2249.out","w",stdout);

	while (scanf ("%d%d",&n,&m)&&(n||m)){

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

		tot=0;int x,y,z,v;

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

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

			link(x,y,z,v),link(y,x,z,v);

		}

		spfa();

		int ans=0;

		for (int i=2;i<=n;++i){

			int mx=2000;

			for (int j=head[i];j!=-1;j=nxt[j]){

				v=to[j];

				if (dis[i]==dis[v]+w[j]) mx=min(mx,c[j]);

			}

			ans+=mx;

		}

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

	

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1000221812215047x):
#include<stdio.h>

#include<string.h>  

#include<math.h>  

  

//#include<map>   

//#include<set>

#include<deque>  

#include<queue>  

#include<stack>  

#include<bitset> 

#include<string>  

#include<iostream>  

#include<algorithm>  

using namespace std;  

  

#define ll long long  

#define INF 0x3f3f3f3f  

#define mod 1000000

#define clean(a,b) memset(a,b,sizeof(a))// 水印 

//spfa

//https://cn.vjudge.net/contest/239171#problem/C 



using namespace std;

//const int maxn=10005;

const int inf=0x3f3f3f3f;

int N,M,k;

int head[10100],cost[10100],dis[10100];

bool vst[10100];

struct node{

    int to,next,dis,cost;

}edge[50100];

void addEdge(int a,int b,int dis,int cost)

{

    edge[k].to=b;

    edge[k].dis=dis;

    edge[k].cost=cost;

    edge[k].next=head[a];

    head[a]=k;

    k++;

}

void spfa(int x)

{

	clean(dis,INF);

	clean(vst,0);

	clean(cost,INF);

//    memset(dis,inf,sizeof(dis));

//    memset(vst,0,sizeof(vst));

//    memset(cost,inf,sizeof(cost));

    queue<int> q;

    dis[x]=0;

    cost[x]=0;

    q.push(x);

    while(!q.empty())

	{

        x=q.front();q.pop();

        vst[x]=0;

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

		{

            node b=edge[i];

            if(dis[b.to]>dis[x]+b.dis)

			{

                if(!vst[b.to])

				{

                    vst[b.to]=1;

                    q.push(b.to);

                }

                dis[b.to]=dis[x]+b.dis;

                cost[b.to]=b.cost;

            }

			else if(dis[b.to]==dis[x]+b.dis)

			{

                if(cost[b.to]>b.cost)

                    cost[b.to]=b.cost;

            }

        }

    }

}



int main()

{

    while(cin>>N>>M,N)

	{

        clean(head,-1);

        k=0;

        for(int i=0;i<M;i++){

            int a,b,d,c;

            cin>>a>>b>>d>>c;

            addEdge(a,b,d,c);

            addEdge(b,a,d,c);

        }

        spfa(1);

        long long re=0;

        for(int i=1;i<=N;i++){

            re+=cost[i];

        }

        cout<<re<<endl;

    }



    return 0;

}