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

#include <stdio.h>

#include <string.h>

#include <queue>

using namespace std;

const int maxn=10050,maxm=20050,inf=0x3f3f3f3f;

struct Edge

{

    int to,next,dis,cos ;

}edge[maxm*2];

struct Pair

{

    int D,V,C;

    Pair(){;}

    Pair(int d,int c,int v)

    {

        D=d,V=v,C=c;

    }

    friend bool operator <(const Pair a,const Pair b)

    {

        if(a.D!=b.D)

        return a.D>b.D;

        else return a.C>b.C;

    }

};

int tot,head[maxn],dist[maxn],cost[maxn];

bool vis[maxn];

void init()

{

    tot=0;

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

}

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

{

    edge[tot].to=v;

    edge[tot].dis=d;

    edge[tot].cos=c;

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

    head[u]=tot++;

}

int dijstra(int start)

{

    memset(vis,false,sizeof(vis));

    memset(dist,inf,sizeof(dist));

    int ans=0;

    dist[start]=0;

   // vis[start]=true;

    priority_queue<Pair>que;

    que.push(Pair(0,0,start));

    while(!que.empty())

    {

        Pair now=que.top();

        que.pop();

        if(vis[now.V])

            continue;

        vis[now.V]=true;

        ans+=now.C;

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

        {

            int to=edge[i].to;

            que.push(Pair(now.D+edge[i].dis,edge[i].cos,to));

        }

    }

    return ans;

}

int main()

{

    int u,v,d,c;

    int n,m;

    while(scanf("%d%d",&n,&m)!=-1)

    {

        init();

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

        for(int 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);

        }

        printf("%d\n",dijstra(1));

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.669756164797336x):
#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;

}