// 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: 1.1864573403038552x):
#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cmath>

#include <deque>

#include <vector>

#include <queue>

#include <string>

#include <cstring>

#include <map>

#include <stack>

#include <set>

using namespace std;

typedef long long ll;

const int inf=0x3f3f3f3f;

const int INF=2147483647;

const double pi=3.1415926535897932384626;

inline ll read(){

	ll x=0,f=1;

	char ch=getchar();

	while(ch<'0'||ch>'9'){

		if(ch=='-') f=-1;

		ch=getchar();

	}

	while(ch>='0'&&ch<='9'){

		x=(x<<1)+(x<<3)+(ch^48);

		ch=getchar();

	}

	return x*f;

}

const int maxn=1e4+5;

int n,m,u,v,dd,cc,ans,d[maxn],c[maxn],vis[maxn];

struct edge{

	int to,dis,cost;

};

vector<edge> g[maxn];

void Dijkstra(){

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

	memset(d,inf,sizeof(d));

	memset(c,inf,sizeof(c));

	d[1]=0;

	c[1]=0;

	ans=0;

	while(1){

		int v=-1;

		for(int u=1;u<=n;u++){

			if(!vis[u]&&(v==-1||d[u]<d[v])) v=u;

		}

		if(v==-1) break;

		vis[v]=1;

		ans+=c[v];

		for(int i=0;i<g[v].size();i++){

			int u=g[v][i].to,dis=g[v][i].dis,cost=g[v][i].cost;

			if(d[u]>d[v]+dis||(d[u]==d[v]+dis&&cost<c[u])){

				d[u]=d[v]+dis;

				c[u]=cost;

			}

		}

	}

}

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++){

			u=read(),v=read(),dd=read(),cc=read();

			g[u].push_back({v,dd,cc});

			g[v].push_back({u,dd,cc});

		}

		Dijkstra();

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

	}

	return 0;

}