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

#include<cstdio>

#include<vector>

#include<cstring>

#include<iostream>

#include<algorithm>

#define RG register

#define LL long long

#define fre(a) freopen(a".in","r",stdin);//freopen(a".out","w",stdout);

using namespace std;

const int MAXN=50000;

int n,m,num;

int head[MAXN],to[MAXN],len[MAXN],cost[MAXN],Next[MAXN];

int dis[MAXN],pre[MAXN],pree[MAXN];

bool vis[MAXN],use[MAXN];

queue<int>que;

void add(int f,int t,int l,int c)

{

   Next[++num]=head[f];

   to[num]=t;

   len[num]=l;

   cost[num]=c;

   head[f]=num;

}

void SPFA()

{

   que.push(1);

   dis[1]=0;

   while(!que.empty())

      {

	 int now=que.front();

	 que.pop(); vis[now]=0;

	 for(int i=head[now];i;i=Next[i])

	    {

	       int son=to[i];

	       if(dis[now]+len[i]<dis[son])

		  {

		     dis[son]=dis[now]+len[i];

		     pre[son]=now;

		     pree[son]=i;

		     if(!vis[son])

			{

			   vis[son]=1;

			   que.push(son);

			}

		  }

	       else if(dis[now]+len[i]==dis[son])

		  {

		     if(cost[i]<cost[pree[son]])

			pree[son]=i,pre[son]=now;

		  }

	    }

      }

}

int main()

{

   //fre("1");

   while(1)

      {

	 scanf("%d%d",&n,&m);

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

	 num=0;

	 memset(head,0,sizeof head);

	 for(int i=1,a,b,c,d;i<=m;i++)

	    {

	       scanf("%d%d%d%d",&a,&b,&c,&d);

	       add(a,b,c,d); add(b,a,c,d);

	    }

	 memset(dis,0x3f3f3f3f,sizeof dis);

	 memset(vis,0,sizeof vis);

	 memset(use,0,sizeof use);

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

	 SPFA();

	 //for(int i=1;i<=n;i++)printf("dis[%d]=%d\n",i,dis[i]);printf("----------------\n");

	 int ans=0;

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

	    for(int j=i;j>1;j=pre[j])

	       if(!use[pree[j]])

		  ans+=cost[pree[j]],use[pree[j]]=1;

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

      }

   return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.3812000098443962x):
#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 



struct node{

	int to,next,dis,cost;

}edge[40100];

int head[10100];

int dis[10100],cost[10100];

bool vst[10100];

int n,m,k;



void spfa(int x)

{

	clean(dis,INF);

	clean(cost,INF);

	clean(vst,0);

	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;

			}

		}

	}

}



void add(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++;

}



int main()

{

	while(cin>>n>>m&&n!=0||m!=0)

	{

		clean(head,-1);

		k=0;

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

		{

			int a,b,d,c;

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

			add(a,b,d,c);

			add(b,a,d,c);

		}

		spfa(1);

		ll res=0;

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

			res=res+cost[i];

		cout<<res<<endl;

	}

}