// Slower C++ solution:
/*************************************************************************

	> File Name: roadconstruction.cpp

	> Author: 

	> Mail: 

	> Created Time: Mon 09 Jul 2018 11:08:56 AM CST

 ************************************************************************/



#include<cstdio>

#include<vector>

#include<queue>

#include<cstring>

#include<algorithm>

using namespace std;



const int INF = 1e9;



struct edge{

    int to,value,cost;

    edge(){}

    edge(int a,int b,int c):to(a),value(b),cost(c){}

};



typedef pair<int,int> P;

vector<vector<edge> > G(20001);

int d[20001];

int dc[20001];

int V,E;

int sum = 0;



void dijkstra(int s){

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

    fill(d,d+20001,INF);

    fill(dc,dc+20001,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.value){

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

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

                dc[e.to] = e.cost; 

            }

            else if(d[e.to]==d[v]+e.value){

                dc[e.to] = min(dc[e.to],e.cost);

            }

        }

    }

}



int main(){

    while(scanf("%d%d",&V,&E)!=-1){

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

        for(int i=0;i<20001;i++)G[i].clear();

        sum = 0;

        for(int i=0;i<E;i++){

            int a,b,c,d;

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

            a--;

            b--;

            G[a].push_back(edge(b,c,d));

            G[b].push_back(edge(a,c,d));

        }

        dijkstra(0);

        for(int i=1;i<V;i++)sum+=dc[i];

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

    }

    return 0;

}




// Faster C++ solution for the same problem (measured speedup: 1.731914669672664x):
#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

struct node

{

    int to, w, c, next;

} edge[50005];

int head[10005], ip, cost[10005], dis[10005], n, m;

bool vis[10005];

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

{

    edge[ip].to = v;

    edge[ip].w = d;

    edge[ip].c = c;

    edge[ip].next = head[u];

    head[u] = ip++;

}

void spfa(int s)

{

    queue<int> q;

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

        cost[i] = dis[i] = INF;

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

    dis[s] = 0;

    cost[s] = 0;

    vis[s] = 1;

    q.push(s);

    while (!q.empty())

    {

        int u = q.front();

        q.pop();

        vis[u] = 0;

        for(int i = head[u];i != -1;i = edge[i].next)

        {

            int to = edge[i].to;

            int w = edge[i].w;

            if(dis[to] > dis[u] + w||(dis[to] == dis[u]+w&&cost[to] > edge[i].c))

            {

                dis[to] = dis[u] + w;

                cost[to] = edge[i].c;

                if(!vis[to])

                {

                    q.push(to);

                    vis[to] = 1;

                }

            }

        }

    }

}

int main()

{

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

    {

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

            break;

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

        ip = 0;

        for (int i = 0; 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);

        }

        spfa(1);

        int ans = 0;

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

            ans += cost[i];

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

    }

    return 0;

}