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

#include<queue>

#include<cstdlib>

#include<cstdio>

#include<cstring>



using namespace std;

const int maxn=4e4+100;

const int inf=0x3f3f3f3f;



struct Edge{

    int next;

    int to;

    int w;

    int  c;



}G[maxn];



int inq[maxn];

int dis[maxn];

int head[maxn];

int k=0;





void adde(int v,int to,int w,int c)//加?

{

    G[k].to=to;//第k条?指向的点

    G[k].w=w;//第k条?的??

    G[k].c=c;

    G[k].next=head[v];//与第k条??同起点的上一条?的?存位置

    head[v]=k++;

}



queue<int>Q;



void spfa(int s)

{

        while(!Q.empty())Q.pop();

        memset(inq,0,sizeof(inq));

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

        dis[s] = 0;

        inq[s] = 1;

        Q.push(s);

        while(!Q.empty())

        {

                int u = Q.front();

                Q.pop();

                inq[u]=0;

                for(int i=head[u];i!=-1;i=G[i].next)//遍?以u?起点的所有?

                {

                        int v=G[i].to;

                        if(dis[v]>dis[u]+G[i].w)

                        {

                                dis[v]=dis[u]+G[i].w;

                                if(inq[v]==0)

                                {

                                    Q.push(v);

                                    inq[v]=1;

                                }

                        }

                }

                inq[u]=0;



        }

}



int main()

{

        int n,m;

        while(scanf("%d%d",&n,&m)!=EOF)

        {

                if(n==0&m==0)

                        return 0;

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



                k=0;

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

                {

                            int a,b,c,d;

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

                            adde(a,b,c,d);

                            adde(b,a,c,d);

                }

                spfa(1);

                int ans=0;

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

                {

                        int mi=inf;

                        for(int j=head[i];j!=-1;j=G[j].next)

                        {

                                if(dis[G[j].to]+G[j].w==dis[i]&&G[j].c<mi)

                                        mi=G[j].c;

                        }

                        ans+=mi;

                }

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

        }

        return 0;



}

// Faster C++ solution for the same problem (measured speedup: 1.1802212051436984x):
#include "cstring"

#include "cstdio"

#include "vector"

#include "queue"

using namespace std;



const int maxn=11000;



struct edge{int to,d,c;};

edge edges[4100000];

int p;



vector<int>g[maxn];



int dis[maxn],vis[maxn],cos[maxn];

int n,m,sn;



void add(int u,int v,int d,int c)

{

	edges[++p].d=d;

	edges[p].to=v;

	edges[p].c=c;

	g[u].push_back(p);

}



int spfa(int s)

{

	memset(cos,0x3f3f3f3f,sizeof(cos));

	memset(dis,0x3f3f3f3f,sizeof(dis));

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

	

	queue<int>qn;

	qn.push(s);

	dis[s]=0;

	cos[s]=0;

	vis[s]=1;

	

	while(!qn.empty())

	{

		int nn=qn.front();qn.pop();

		vis[nn]=0;

		for(int i=0,d=g[nn].size();i<d;i++)

		{

			edge &e= edges[g[nn][i]];

			if(dis[e.to]>dis[nn]+e.d || ((dis[e.to]==dis[nn]+e.d) && cos[e.to]>e.c))

			{

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

				cos[e.to]=e.c;

				

				if(!vis[e.to])

				{

					qn.push(e.to);

					vis[e.to]=1;

				}

			}

		}	

	}

	return 0;

}



int main()

{

	//freopen("q.txt","r",stdin);

	int u,v,d,c;

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

	{

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

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

			g[i].clear();

		p=0;

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

		{

			scanf("%d%d%d%d",&u,&v,&d,&c);

			add(u,v,d,c);

			add(v,u,d,c);

		}

		int ans=0;

		spfa(1);

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

			ans+=cos[i];

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

	}

	return 0;

}