// Original C++ solution (slower):
#include <bits/stdc++.h>

using namespace std;

#define inf 0x3f3f3f3f

const int maxn = 10000+5;

int N,M,dis[maxn],vis[maxn],cost[maxn];

struct edge

{

    int v,d,c;

    edge(int A,int B,int C):v(A),d(B),c(C) {}

};

vector<edge> G[maxn];

queue<int> que;



void spfa()

{

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

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

    memset(cost, inf, sizeof(cost));

    vis[1] = 1;

    dis[1] = 0;

    cost[1] = 0;

    que.push(1);

    while(!que.empty())

    {

        int u = que.front();

        que.pop();

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

        {

            edge &e = G[u][i];

            if(dis[e.v] > dis[u] + e.d)

            {

                dis[e.v] = dis[u] + e.d;

                cost[e.v] = e.c;

                if(!vis[e.v])

                {

                    vis[e.v] = 1;

                    que.push(e.v);

                }

            }

            else if(dis[e.v] == dis[u] + e.d && cost[e.v] > e.c)

            {

                cost[e.v] = e.c;

                if(!vis[e.v])

                {

                    vis[e.v] = 1;

                    que.push(e.v);

                }

            }

        }

        vis[u] = 0;

    }

    int ans = 0;

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

    ans += cost[i];

    cout << ans << endl;

}





//void spfa()

//{

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

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

//    memset(cost, inf, sizeof(cost));

//    vis[1] = 1;

//    dis[1] = 0;

//    cost[1] = 0;

//    que.push(1);

//    while(!que.empty())

//    {

//        int u = que.front();

//        que.pop();

//        for(int i=0; i<G[u].size(); ++i)

//            {

//            edge &e = G[u][i];

//            if(dis[e.v] > dis[u] + e.d)

//            {

//                dis[e.v] = dis[u] + e.d;

//                cost[e.v] = e.c;

//                if(!vis[e.v])

//                {

//                    vis[e.v] = 1;

//                    que.push(e.v);

//                }

//            }

//            else if(dis[e.v] == dis[u] + e.d && cost[e.v] > e.c)

//            {

//                cost[e.v] = e.c;

//                if(!vis[e.v])

//                {

//                    vis[e.v] = 1;

//                    que.push(e.v);

//                }

//            }

//        }

//        vis[u]=0;

//    }

//    int ans = 0;

//    for(int i=1; i<=N; ++i)

//        ans+=cost[i];

//    cout<<ans<<endl;

//}



int main()

{

    while(cin>>N>>M)

    {

        if(N==0&&M==0)

            break;

        int u,v,d,c;

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

        {

            cin>>u>>v>>d>>c;

            G[u].push_back(edge(v,d,c));

            G[v].push_back(edge(u,d,c));

        }

        spfa();

//        /// clear

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

            G[i].clear();

    }

    return 0;

}

// Optimized solution to the same problem (faster):
#include <cstdio>

#include <cstring>

#include <algorithm>



using namespace std;



const int inf = 0x3f3f3f3f;

const int N = 10414;

const int M = 40414;



struct Edge{

	int u, v, d, c;

	int next;

}edge[M];



int cnt, head[N];

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

int op, tp, link[18014];



void add_edge(int u, int v, int d, int c);

void spfa(int n);



int main(){

	int n, m, i, u, v, d, c;

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

		cnt = 0;

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

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

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

			add_edge(u, v, d, c);

			add_edge(v, u, d, c);

		}

		spfa(n);

	}

	return 0;

}

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

	edge[cnt].u = u;

	edge[cnt].v = v;

	edge[cnt].d = d;

	edge[cnt].c = c;

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

	head[u] = cnt++;

	return;

}

void spfa(int n){

	int i, u, v, d, c, sum;

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

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

	memset(cost, inf, sizeof(cost));

	op = tp = 0;

	vis[1] = 1, dis[1] = 0, cost[1] = 0;

	link[tp++] = 1;

	while(op < tp){

		u = link[op++];

		vis[u] = 0;

		for(i = head[u]; ~i; i = edge[i].next){

			v = edge[i].v, d = edge[i].d, c = edge[i].c;



			if(dis[v] > dis[u] + d || (dis[v] == dis[u] + d && cost[v] > c)){

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

				cost[v] = c;

				if(!vis[v]){

					vis[v] = 1;

					link[tp++] = v;

				}

			}

		}

	}

	sum = 0;

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

		sum += cost[i];

	}

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

	return;

}




// Fastest known solution for this problem: