// 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: 1.8133778657212993x):
#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cmath>

#include <deque>

#include <vector>

#include <queue>

#include <string>

#include <cstring>

#include <map>

#include <stack>

#include <set>

using namespace std;

typedef long long ll;

const int inf=0x3f3f3f3f;

const int INF=2147483647;

const double pi=3.1415926535897932384626;

inline ll read(){

	ll x=0,f=1;

	char ch=getchar();

	while(ch<'0'||ch>'9'){

		if(ch=='-') f=-1;

		ch=getchar();

	}

	while(ch>='0'&&ch<='9'){

		x=(x<<1)+(x<<3)+(ch^48);

		ch=getchar();

	}

	return x*f;

}

const int maxn=1e4+5;

int n,m,u,v,dd,cc,ans,d[maxn],c[maxn],vis[maxn];

struct edge{

	int to,dis,cost;

};

vector<edge> g[maxn];

void Dijkstra(){

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

	memset(d,inf,sizeof(d));

	memset(c,inf,sizeof(c));

	d[1]=0;

	c[1]=0;

	ans=0;

	while(1){

		int v=-1;

		for(int u=1;u<=n;u++){

			if(!vis[u]&&(v==-1||d[u]<d[v])) v=u;

		}

		if(v==-1) break;

		vis[v]=1;

		ans+=c[v];

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

			int u=g[v][i].to,dis=g[v][i].dis,cost=g[v][i].cost;

			if(d[u]>d[v]+dis||(d[u]==d[v]+dis&&cost<c[u])){

				d[u]=d[v]+dis;

				c[u]=cost;

			}

		}

	}

}

int main(){

	while(~scanf("%d%d",&n,&m)&&(n+m)){

		for(int i=1;i<=n;i++) g[i].clear();

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

			u=read(),v=read(),dd=read(),cc=read();

			g[u].push_back({v,dd,cc});

			g[v].push_back({u,dd,cc});

		}

		Dijkstra();

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

	}

	return 0;

}