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

#include<vector>

#include<queue>

#include<algorithm>

#include<cstring>

using namespace std;

const int maxn  = 1e4+10;

const int INF = 0x3f3f3f3f;

typedef pair<int,int> P;

struct edge{

	int to,dis,cost;

		

};



int d[maxn];

int value[maxn];



int N,M;



int dijkstra(vector<edge>G[])

{



	memset(d,INF,sizeof(d));

	//memset(value,INF,sizeof(value));

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

		

	d[1] = 0;

	value[1] = 0;

	que.push(P(d[1],1));

	

	int res = 0;

	while(!que.empty())

	{

		P p  = que.top(); que.pop();

		

		int v = p.second;

		if(d[v] < p.first)

			continue;

			

		res += value[v];

		

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

		{

			edge e = G[v][i];

			if(d[e.to] == d[v] + e.dis)

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

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

			{

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

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

				

				value[e.to] = e.cost;

			}

		}

	}

	return res;

	

}



int main()

{



	//freopen("c:\\users\\administrator\\desktop\\in.txt","r",stdin);

	while(cin >> N >> M, N||M)

	{

		

		vector<edge> G[maxn];

		for(int i =0; i < M; i++)

		{

			int u,v,d,c;

			edge e;

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

			e.to= v, e.dis= d, e.cost =c;

			G[u].push_back(e);

			e.to= u;

			G[v].push_back(e);	

		}

		

		int res = dijkstra(G);

		cout << res <<endl;

	}		

} 

// Faster C++ solution for the same problem (measured speedup: 1.2456192094085945x):
#include <cstdio>

#include <cstring>

#include <algorithm>

#include <queue>



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 op, tp, link[N];

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

queue<int>q;



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++;

}

void spfa(int n)

{

    int v, d, c;

    while(!q.empty())q.pop();

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

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

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

    dis[1]=0;

    cost[1]=0;

    vis[1]=true;

    q.push(1);

    while(!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=false;

        for(int i=head[u]; i!=-1; 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))//有多条最短路时，取花费最小的

            {

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

                cost[v] = c;

                if(!vis[v])

                {

                    q.push(v);

                    vis[v]=true;

                }

            }

        }

    }

    int sum = 0;

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

    	sum += cost[i];

    }

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

    return;

}