// Original C++ solution (slower):
#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;

}

// 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: