// 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: 1.2379759626178257x):
#include<iostream>

#include<cstdio>

#include<cstdlib>

#include<string>

#include<cstring>

#include<algorithm>

#include<queue>

#include<vector>

#define N 20100

#define M 50010

#define rg register

using namespace std;

typedef long long ll;

typedef double db;

int n,m,tot=0;

int dis[N],head[N],vis[N];

int nxt[M],to[M],w[M],c[M];

void link(int x,int y,int z,int v){

	nxt[tot]=head[x],to[tot]=y,w[tot]=z,c[tot]=v,head[x]=tot++;

}

void spfa(){

	queue <int> q;

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

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

	q.push(1),dis[1]=0,vis[1]=1;

	while (!q.empty()){

		int x=q.front();q.pop();

		for (int i=head[x];i!=-1;i=nxt[i]){

			int v=to[i];

			if (dis[v]<=dis[x]+w[i]) continue;

			dis[v]=dis[x]+w[i];

			if (!vis[v]) vis[v]=1,q.push(v);

		}

		vis[x]=0;

	}

}

int main(){

//	freopen ("2249.in","r",stdin);

//	freopen ("2249.out","w",stdout);

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

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

		tot=0;int x,y,z,v;

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

			scanf ("%d%d%d%d",&x,&y,&z,&v);

			link(x,y,z,v),link(y,x,z,v);

		}

		spfa();

		int ans=0;

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

			int mx=2000;

			for (int j=head[i];j!=-1;j=nxt[j]){

				v=to[j];

				if (dis[i]==dis[v]+w[j]) mx=min(mx,c[j]);

			}

			ans+=mx;

		}

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

	

	}

	return 0;

}