// 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: 1.455632310601565x):
/*************************************************************************

	> File Name: roadconstruction.cpp

	> Author: 

	> Mail: 

	> Created Time: Mon 09 Jul 2018 11:08:56 AM CST

 ************************************************************************/



#include<cstdio>

#include<vector>

#include<queue>

#include<cstring>

#include<algorithm>

using namespace std;



const int INF = 1e9;



struct edge{

    int to,value,cost;

    edge(){}

    edge(int a,int b,int c):to(a),value(b),cost(c){}

};



typedef pair<int,int> P;

vector<vector<edge> > G(20001);

int d[20001];

int dc[20001];

int V,E;

int sum = 0;



void dijkstra(int s){

    priority_queue<P, vector<P>, greater<P> > que;

    fill(d,d+20001,INF);

    fill(dc,dc+20001,INF);

    d[s] = 0;

    que.push(P(0,s));

    while(!que.empty()){

        P p = que.top();

        que.pop();

        int v = p.second;

        if(d[v]<p.first)continue;

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

            edge e = G[v][i];

            if(d[e.to]>d[v]+e.value){

                d[e.to] = d[v] + e.value;

                que.push(P(d[e.to],e.to));

                dc[e.to] = e.cost; 

            }

            else if(d[e.to]==d[v]+e.value){

                dc[e.to] = min(dc[e.to],e.cost);

            }

        }

    }

}



int main(){

    while(scanf("%d%d",&V,&E)!=-1){

        if(V==0&&E==0)break;

        for(int i=0;i<20001;i++)G[i].clear();

        sum = 0;

        for(int i=0;i<E;i++){

            int a,b,c,d;

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

            a--;

            b--;

            G[a].push_back(edge(b,c,d));

            G[b].push_back(edge(a,c,d));

        }

        dijkstra(0);

        for(int i=1;i<V;i++)sum+=dc[i];

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

    }

    return 0;

}