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

#include <cstdio>

#include <queue>

#include <string.h>



using namespace std;



#define MAXN 10001

#define INF 999999999





struct Edge

{

	int u, v, next, d, c;

}edge[MAXN * 4];



int head[MAXN], e;

int n, m;

int total;

int dis[MAXN];

int cost[MAXN];

bool vis[MAXN];



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

{

	edge[e].u = u;

	edge[e].v = v;

	edge[e].d = d;

	edge[e].c = c;

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

	head[u] = e++;

}



void init()

{

	e = 0;

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

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

}



queue <int> q;



void solve()

{

	while (!q.empty())

	{

		q.pop();

	}

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

	{

		dis[i] = INF;

		cost[i] = INF;

	}

	

	int cur, next, ans = 0;

	q.push(1);

	vis[1] = true;

	dis[1] = 0;

	cost[1] = 0;

	

	while (!q.empty())

	{

		cur = q.front();

		q.pop();

		vis[cur] = false;

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

		{

			int v = edge[i].v;

				if (dis[v] > dis[cur] + edge[i].d)

				{

					dis[v] = dis[cur] + edge[i].d;

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

					if(!vis[v])

				     {

					vis[v] = true;

					q.push(v);

				    }

				}

				else if (dis[v] == dis[cur] + edge[i].d && cost[v] > edge[i].c)

	             {

			

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

					if(!vis[v])

			     	{

					vis[v] = true;

					q.push(v);

				    }

				}

				

		}

		

		

	}

	

	int ss = 0;

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

	{

		ss += cost[i];

	}

	

	cout << ss << endl;

}



void input()

{

	int u, v, d, c;

	

	while (cin >> n >> m)

	{

		total = 0;

		if (!n && !m)

		{

			break;

		}

		init();

		

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

		{

			cin >> u >> v >> d >> c;

			add(u, v, d, c);

			add(v, u, d, c);

			total += 2 * c;

		}

		

		solve();

	}

}



int main()

{

	std::ios::sync_with_stdio(false);

	input();

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.5766957445213627x):
#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;

}