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

#include <cstring>

const int SIZE = 10010;

const int MAX = 0x3f3f3f3f;



typedef struct Road

{

	int from;

	int to;

	int length;

	int cost;

	int next;

} Road;



int head[SIZE];

int dis[SIZE];

Road roads[SIZE * 5];

int front[SIZE];

bool visit[SIZE];



int city, road, capital;



void init()

{

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

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

	memset(visit, false, sizeof(visit));

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

	{

		dis[i] = MAX;

	}

	dis[1] = 0;

}



void dijkstra()

{

	while (true)

	{

		int pos = -1;

		for (int i = 1; i <= city; ++i)

		{

			if (!visit[i] && (pos == -1 || dis[pos] > dis[i]))

			{

				pos = i;

			}

		}

		if (pos == -1)

		{

			break;

		}

		visit[pos] = true;

		for (int i = head[pos]; i != -1; i = roads[i].next)

		{

			int to = roads[i].to;

			if (dis[to] > dis[pos] + roads[i].length)

			{

				dis[to] = dis[pos] + roads[i].length;

				front[to] = i;

			}

			else if ((dis[to] == dis[pos] + roads[i].length) && front[to] != -1 && roads[i].cost < roads[front[to]].cost)

			{

				front[to] = i;

			}

		}

	}

}



int main()

{

	while (true)

	{

		std::cin >> city >> road;

		if (city == 0 && road == 0)

		{

			break;

		}

		init();

		int en = 0;

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

		{

			std::cin >> roads[en].from >> roads[en].to >> roads[en].length >> roads[en].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

			roads[en].from = roads[en - 1].to;

			roads[en].to = roads[en - 1].from;

			roads[en].length = roads[en - 1].length;

			roads[en].cost = roads[en - 1].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

		}

		dijkstra();

		int result = 0;

		for (int i = 1; i <= city; ++i)

		{

			if (front[i] != -1)

			{

				result += roads[front[i]].cost;

			}

		}

		std::cout << result << std::endl;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.684025569499175x):
#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;

}