// 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: 1.1527356572609295x):
#include <bits/stdc++.h>

using namespace std;

const int maxn = 2e4+9;

const int inf = 0x3f3f3f3f;

typedef long long int ll;

typedef pair<int,int> pi;

struct {

    int v,nex,d,c;

}e[maxn*2];

int in[maxn];

int dis[maxn];

int head[maxn];

int tot;

void addedge(int u,int v,int d,int c){

    e[tot] ={v,head[u],d,c};

    head[u] = tot++;

}

int dd[maxn];

priority_queue<pi> qq;

int main()

{

    int n,m;

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

            tot =0;

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

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

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

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

        memset(in,0,sizeof(in));



        while(!qq.empty()){

            qq.pop();

        }

        qq.push(pi(0,1));

        dis[1] =0;

        dd[1] = 0;



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

            int u,v,d,c;

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

            addedge(u,v,d,c);

            addedge(v,u,d,c);

        }

        while(!qq.empty()){

            pi now = qq.top();

            qq.pop();

            int pp = now.second;

            if(in[pp]==1) continue;

            in[pp] = 1;

            for(int i=head[pp];i!=-1;i=e[i].nex){

                int v= e[i].v;

                int d = e[i].d;

                if(in[v]==1) continue;

                if( dis[pp]+d<dis[v]){

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

                    dd[v] = e[i].c;

                    qq.push(pi(-dis[v],v));

                }else if(dis[pp]+d==dis[v]){

                    dd[v] = min(dd[v],e[i].c);

                }

            }

        }

        int ans = 0;

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

            ans+=dd[i];

        }

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

    }

    return 0;

}