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

#include <cstring>

#include <queue>

#define inf 0x3f3f3f3f

#define maxm 10005

#define maxn 40005



using namespace std;



int m,n;

long long edgenum,head[maxm],dis[maxm],num[maxm],ans;

bool vis[maxm];



struct node

{

    int from,to,len,cost,next;

}edge[maxn];



void init()

{

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

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

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

    memset(num,inf,sizeof(num));

    edgenum=0;

}



void add(int u,int v,int len,int cost)

{

    node tp={u,v,len,cost,head[u]};

    edge[edgenum]=tp;

    head[u]=edgenum++;

}



long long SPFA(int st)

{

     queue<int> q;

     q.push(st);

     vis[st]=1;

     dis[st]=0;

     num[st]=0;

     ans=0;

     while(!q.empty())

     {

          int tmp=q.front();

          q.pop();

          vis[tmp]=0;

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

          {

                if((dis[edge[i].to]>dis[tmp]+edge[i].len)||((dis[edge[i].to]==dis[tmp]+edge[i].len)&&(num[edge[i].to]>edge[i].cost)))

                {

                    dis[edge[i].to]=dis[tmp]+edge[i].len;

                    num[edge[i].to]=edge[i].cost;

                    if(!vis[edge[i].to])

                    {

                        q.push(edge[i].to);

                        vis[edge[i].to]=1;

                    }

                }

          }

     }

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

        ans+=num[i];

     return ans;

}



int main()

{

    int u,v,len,cost;

    while(cin>>m>>n&&m)

    {

        init();

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

        {

            cin>>u>>v>>len>>cost;

            add(u,v,len,cost);

            add(v,u,len,cost);

        }

        cout<<SPFA(1)<<endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1300570323373784x):
#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;

}