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

#include <queue>

#include <cstdio>

#include <algorithm>

#include <cstring>

using namespace std;

struct sdsd

{

    int from,to,value,time;

};

bool operator < (sdsd a,sdsd b)

{

    return a.time>b.time;

}

sdsd zz[45555];

int sb[15555],sc[15555],svalue[15555],stime1[155555],sd[15555];

int main ()

{

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

    int n,m;

    while (cin >>n>>m)

    {

        if (!n) break;

        for (int i=0;i<15555;i++)

        {

            svalue[i]=1e9+1;

            stime1[i]=1e9+1;

        }

        svalue[1]=0;

        stime1[1]=0;

        memset (sc,0,sizeof(sc));

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

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

        memset (sd,0,sizeof(sd));

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

        {

            int a,b,c,d;

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

            zz[2*i].to=a;

            zz[2*i].from=sb[b];

            sb[b]=2*i;

            zz[2*i].value=d;

            zz[2*i].time=c;

            zz[2*i+1].to=b;

            zz[2*i+1].from=sb[a];

            sb[a]=2*i+1;

            zz[2*i+1].value=d;

            zz[2*i+1].time=c;

        }

        priority_queue <int > se;

        int x=sb[1];

        while (x!=-1)

        {

            if (stime1[1]+zz[x].time<stime1[zz[x].to])

            {

                stime1[zz[x].to]=stime1[1]+zz[x].time;

                svalue[zz[x].to]=zz[x].value;

                sd[zz[x].to]=1;

                if (!sc[zz[x].to])

                {

                    se.push(zz[x].to);

                    sc[zz[x].to]=1;

                }

            }

            else if (stime1[1]+zz[x].time==stime1[zz[x].to])

            {

                if (zz[x].value<svalue[zz[x].to])

                {

                    svalue[zz[x].to]=zz[x].value;

                    sd[zz[x].to]=1;

                    if (!sc[zz[x].to])

                    {

                        se.push(zz[x].to);

                        sc[zz[x].to]=1;

                    }

                }

            }

            x=zz[x].from;

        }

        while (!se.empty())

        {

            int tt=se.top();

            se.pop();

            sc[tt]=0;

            int t=sb[tt];

        while (t!=-1)

        {

            if (stime1[tt]+zz[t].time<stime1[zz[t].to])

            {

                stime1[zz[t].to]=stime1[tt]+zz[t].time;

                svalue[zz[t].to]=zz[t].value;

                sd[zz[t].to]=tt;

                //cout <<zz[x].to<<" "<<sd[zz[x].to]<<endl;

                if (!sc[zz[t].to])

                {

                    se.push(zz[t].to);

                    sc[zz[t].to]=1;

                }

            }

            else if (stime1[tt]+zz[t].time==stime1[zz[t].to])

            {

            /*cout <<tt<<" "<<zz[t].to<<endl;

            cout<<svalue[tt]<<" "<< zz[t].value<<" "<<svalue[zz[t].to]<<endl;

            cout <<endl;*/

                if (zz[t].value<svalue[zz[t].to])

                {

                    svalue[zz[t].to]=zz[t].value;

                    sd[zz[t].to]=tt;

                    if (!sc[zz[t].to])

                    {

                        se.push(zz[t].to);

                        sc[zz[t].to]=1;

                    }

                }

            }

            t=zz[t].from;

        }



        }

        int s=0;

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

        {

            s+=svalue[i];

        }

        cout <<s<<endl;

    }

}




// Faster C++ solution for the same problem (measured speedup: 2.1119960608420008x):
#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;

}