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

#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int inf =0x3f3f3f3f;

const int MAXN=10005;

struct node

{

    int next, to, d, c;

} G[2000005];

int cur, n;

bool vis[MAXN];

int cost[MAXN];

int dist[MAXN];

int head[MAXN];

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

{

    G[cur].to=v;

    G[cur].c=c;

    G[cur].d=d;

    G[cur].next=head[u];

    head[u]=cur++;

}

queue<int>q;

void spfa(int s)

{



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

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

    fill(cost+1,cost+n+1,inf);

    fill(dist+1,dist+n+1,inf);

    q.push(s);

    dist[s]=0;

    cost[s]=0;

    while(!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=false;

        for(int i=head[u]; ~i; i=G[i].next)

        {

            int v=G[i].to;

            if(dist[v]>dist[u]+G[i].d||(dist[v]==dist[u]+G[i].d&&cost[v]>G[i].c))

            {

                dist[v]=dist[u]+G[i].d;

                cost[v]=G[i].c;

                if(!vis[v])

                {

                    vis[v]=true;

                    q.push(v);

                }

            }

        }

    }

}

int main()

{

    int m;

    int u, v, d, c;

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

    {

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

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

        cur=0;

        while(m--)

        {

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

            add(u, v, d, c);

            add(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;

}

// Faster C++ solution for the same problem (measured speedup: 2.516368222547152x):
#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;

}