// 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: 1.8923423908013604x):
#include<iostream>

#include<queue>

#include<functional>

#include<cstring>



using namespace std;



#define maxn 10240 

#define INF 0x3f3f3f3f;



typedef struct edge{

	int to,dis,cos;

	edge(){}

	edge(int to,int dis,int cos):to(to),dis(dis),cos(cos){}

};

typedef pair<int ,int> P;



vector<edge>G[maxn];



int d[maxn];

int v;//定点



void dijkstra(int s){

	priority_queue<P,vector<P>,greater<P> > que;//优先输出小数据；

	memset(d,0x3f,sizeof(d));

	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.dis)

			{

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

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

			}

		}

	}	

} 

int main()

{

	int m;

	while(cin>>v>>m)

	{

		if(v==0&&m==0)break;

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

		{

			G[i].clear();

		}

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

		{

			int u,v,d,c;

			cin>>u>>v>>d>>c;

			u--,v--;

			G[u].push_back(edge(v,d,c));

			G[v].push_back(edge(u,d,c)); 

		}

		dijkstra(0);

		int ans=0;

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

		{

			int min=INF;

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

			{

				if(d[G[i][j].to]+G[i][j].dis==d[i]&&G[i][j].cos<min)

				{

					min=G[i][j].cos;

				}

				

			} 

			ans+=min;

		}cout<<ans<<endl;

	}

	return 0;

}