// 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: 1.2974521668774714x):
#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<queue>

#include<vector>

#include<stack>

#define ls k<<1

#define rs k<<1|1

#define RG register

#define MAXN 50010

#define LL long long int

using namespace std;

const int INF=0x7fffffff;

struct node{

	int next;

	int to;

	int w;

	int c;

}t[MAXN];

int head[MAXN];

int num;

int dis[MAXN],vis[MAXN],cost[MAXN];

int n,m;

void add(int from,int to,int w,int c)

{

	t[++num].next=head[from];

	t[num].to=to;

	t[num].w=w;

	t[num].c=c;

	head[from]=num;

}

void spfa()

{

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

		{

			dis[i]=INF;vis[i]=0;cost[i]=INF;

		}

	cost[1]=dis[1]=0;vis[1]=1;

	queue<int>q;q.push(1);

	while(!q.empty())

		{

			int u=q.front();q.pop();vis[u]=0;

			for(int i=head[u];i;i=t[i].next)

				{

					int v=t[i].to;

					if(dis[v]>dis[u]+t[i].w||(dis[v]==dis[u]+t[i].w&&cost[v]>t[i].c))

						{

							dis[v]=dis[u]+t[i].w;

							cost[v]=t[i].c;

							if(!vis[v])

								{

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

								}

						}

				}

		}

}

int main()

{

//	freopen("1.in","r" ,stdin);

	//freopen("1.out","w",stdout);

	while(1)

		{

			scanf("%d%d",&n,&m);if(n==0&&m==0) break;

			int x,y,z,k;

			memset(head,0,sizeof(head));num=0;

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

				{

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

					add(x,y,z,k);add(y,x,z,k);

				}

			spfa();

			int ans=0;

			for(int i=1;i<=n;i++) ans+=cost[i];

			cout<<ans<<endl;

		}

	return 0;

}