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

#include <cstring>

#include <cstdio>

#include <vector>

#include <queue>

#define maxn 10005

#define MAXN 10005

#define inf 0x0f0f0f0f



using namespace std;



int head[maxn],tol,dis[maxn],vis[maxn],n,m,mi[maxn];

int cost[MAXN];



struct node

{

    int a,len,to,next,cost;

}edge[50005];







void INIT()

{

    tol=0;

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

}



void add(int a,int b,int c,int d)

{

    edge[tol].to=b;

    edge[tol].len=c;

    edge[tol].cost=d;

    edge[tol].next=head[a];

    head[a]=tol++;

}



void SPFA()

{

    int i,a,p;



    for(i=0;i<n;i++)

        dis[i]=inf,vis[i]=0,cost[i]=inf;

    queue<int> que;

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

    que.push(0);

    while(!que.empty())

    {

        a=que.front(),que.pop();

        vis[a]=0;

        for(p=head[a];p!=-1;p=edge[p].next)

        {

            if(dis[edge[p].to]>dis[a]+edge[p].len)

            {

                dis[edge[p].to]=dis[a]+edge[p].len;

                cost[edge[p].to]=edge[p].cost;

                if(!vis[edge[p].to])

                {

                    vis[edge[p].to]=1;

                    que.push(edge[p].to);

                }

            }

            if(dis[edge[p].to]==dis[a]+edge[p].len&&cost[edge[p].to]>edge[p].cost)

            {

            //    puts("Debug");

                cost[edge[p].to]=edge[p].cost;

                if(!vis[edge[p].to])

                {

                    vis[edge[p].to]=1;

                    que.push(edge[p].to);

                }

            }

        }

    }

}



int main(){

    int i,j;

    int a,b,l,c;

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

       INIT();

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

            scanf("%d%d%d%d",&a,&b,&l,&c);

            a--;

            b--;

            add(a,b,l,c);

            add(b,a,l,c);

       }

       SPFA();

       int res=0;

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

           // printf("Debug :%d\n",father[i]);

            res+=cost[i];

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

       //bfs();

    }

    return 0;

}

/*

5 6

1 2 2 2

2 3 1 1

1 4 1 1

3 5 1 1

4 2 2 1

4 5 1 1



*/

// Faster C++ solution for the same problem (measured speedup: 2.491073646816189x):
#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;

}