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

#include<iostream>

#include<algorithm>

#include<vector>

#include<queue>

#define MAX_V 10006

#define INF 0x3fffffff

using namespace std;

struct edge{

    int to,cost,dis;

    };

typedef pair<int,int> P;

int V;

vector<edge> G[MAX_V];

int d[MAX_V];



void dij(int s){

    priority_queue<P,vector<P>,greater<P> > que;

    fill(d,d+V,INF);

    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.cost){

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

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

            }

        }

    }

    int ans=0;



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

        int mimcost=INF;

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

            if(d[G[i][j].to]+G[i][j].cost==d[i]&&G[i][j].dis<mimcost){



                mimcost=G[i][j].dis;

                //cout<<mimcost<<endl;

            }

        }

        //cout<<mimcost<<endl;

        ans+=mimcost;

    }

    cout<<ans<<endl;



}



int main(){

   // freopen("1.txt","r",stdin);

    int M;

    while(cin>>V>>M){

        if(V==0&&M==0)break;

        for(int i=0;i<V;i++)G[i].clear();

        while(M--){

            int a,b,t,c;

            cin>>a>>b>>t>>c;

            a--;b--;

            edge tmp;

            tmp.to=b;

            tmp.cost=t;

            tmp.dis=c;

            G[a].push_back(tmp);

            tmp.to=a;

            G[b].push_back(tmp);

        }

        dij(0);

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.216347298647775x):
#include <cstdio>

#include <cstdlib>

#include <iostream>

#include <cstring>

#include <cmath>

#include <ctime>

#include <algorithm>

#include <vector>

#include <set>

#include <queue>

#include <map>

#include <stack>

#include <bitset>

using namespace std;

typedef int gitype;

gitype gi () {

    gitype ret=0; char ch=getchar();

    while((ch<'0' || ch>'9') && ch!='-') ch=getchar();

    char c=ch=='-'?getchar():ch;

    while(c>='0' && c<='9') ret=ret*10+c-'0',c=getchar();

    return ch=='-'?-ret:ret;

}

const int N = 10010;

const int M = 100010;

int n,m,st[N],vis[N],dis[N],pt[M],nxt[M],w[M],c[M],cost[N],ent=0;

void link (int u,int v,int _w,int _c) {

    pt[++ent]=v; nxt[ent]=st[u]; st[u]=ent; w[ent]=_w; c[ent]=_c;

    pt[++ent]=u; nxt[ent]=st[v]; st[v]=ent; w[ent]=_w; c[ent]=_c;

}

queue<int> q;

int main () {

    while(scanf("%d%d",&n,&m)==2 && (n || m)) {

        memset(st,0,sizeof(st)); ent=0;

        int u,v,_w,_c;

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

            u=gi(); v=gi(); _w=gi(); _c=gi(); link(u,v,_w,_c);

        }

        for(int i=1;i<=n;i+=1) dis[i]=1e9 + 5;

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

        while(!q.empty()) {

            int r=q.front(); q.pop(); vis[r]=false;

            for(int i=st[r];i;i=nxt[i]) {

                if(dis[pt[i]] > dis[r]+w[i]) {

                    dis[pt[i]] = dis[r]+w[i]; cost[pt[i]] = c[i];

                    if(!vis[pt[i]]) {

                        vis[pt[i]] = true; q.push(pt[i]);

                    }

                } else if(dis[pt[i]] == dis[r]+w[i]) {

                    cost[pt[i]] = min(cost[pt[i]], c[i]);

                }

            }

        }

        int ans = 0;

        for(int i=2;i<=n;i+=1) ans += cost[i];

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

    }

    return 0;

}