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

#include <cstdio>

#include <cstring>

#include <vector>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

const int MAXN = 10005;

struct Edge

{

    int to, w, cost;

    Edge() {}

    Edge(int a, int b, int c): to(a), w(b), cost(c) {}

    bool operator < (const Edge &r) const

    {

        return w > r.w || w == r.w && cost > r.cost;

    }

};

vector<Edge> G[MAXN];

bool vis[MAXN];

int dist[MAXN];

int cost[MAXN];

int pre[MAXN];

void Dijkstra(int n, int start)

{

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

        vis[i] = 0, dist[i] = cost[i] = INF;

    priority_queue<Edge> que;

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

    dist[start] = cost[start] = 0;

    pre[start] = start;

    Edge tmp;

    while (!que.empty())

    {

        tmp = que.top();

        que.pop();

        int u = tmp.to;

    //    cout << tmp.to << endl;

        if (vis[u]) continue;

        vis[u] = 1;

        for (int i = 0; i < G[u].size(); i++)

        {

            int v = G[u][i].to;

            int w = G[u][i].w;

    //        cout << v << " " << w << " " << G[u][i].cost << endl;

    //        cout << dist[v] << " " << cost[v] << endl;

     //       cout << dist[u] << " " << cost[u] << endl;

            if (!vis[v] && dist[v] > dist[u] + w)

            {

                dist[v] = dist[u] + w;

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

      //          cout <<"s1  " << v << " " << dist[v] << " " << cost[v] << endl;

                pre[v] = u;

                que.push(Edge(v, dist[v], cost[v]));

            }

            else if (!vis[v] && dist[v] == dist[u]+w && cost[v] >  G[u][i].cost)

            {

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

         //       cout << "s2  " <<  v << " " << dist[v] << " " << cost[v] << endl;

                pre[v] = u;

                que.push(Edge(v, dist[v], cost[v]));

            }

        }

    }

   // for (int i = 2; i <= n; i++) cout << cost[i] - cost[pre[i]] <<endl;

}

int n, m;

int main()

{

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

    {

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

            G[i].clear();

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

        {

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

            G[u].push_back(Edge(v, d, c));

            G[v].push_back(Edge(u, d, c));

        }

        Dijkstra(n, 1);

        int ans = 0;

        for (int i = 2; i <= n; i++) ans += cost[i];

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

    }

}

// Faster C++ solution for the same problem (measured speedup: 1.1298389703834195x):
#include<cstdio>

#include<algorithm>

#include<queue>

#include<iostream>

#include<cstring>

using namespace std;

const int maxn = 10050, maxe = 2005000, inf = 1e9;

struct node {

	int to;

	int w;

	int c;

	int next;

};

node edge[maxe];

int head[maxn];

int ip;

void init()

{

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

	ip = 0;

}

void addedge(int u, int v, int w, int c)

{

	edge[ip].to = v;

	edge[ip].c = c;

	edge[ip].w = w;

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

	head[u] = ip++;

}

int cost[maxn], dis[maxn], vis[maxn];

queue<int>q;

void spfa(int s, int n)

{

	while (!q.empty())

		q.pop();

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

		dis[i] = cost[i] = inf;

	memset(vis, 0, sizeof(vis));

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

	q.push(s);

	while (q.size())

	{

		int u = q.front();

		q.pop();

		vis[u] = 0;

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

		{

			int to = edge[i].to, val = edge[i].w;

			if (dis[to] > dis[u] + val || (dis[to] == dis[u] + val&&cost[to] > edge[i].c))

			{

				dis[to] = dis[u] + val;

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

				if (!vis[to])

				{

					q.push(to);

					vis[to] = 1;

				}

			}

		}

	}

}

int main()

{

	int n, m, u, v, w, c;

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

	{

		init();

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

		{

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

			addedge(u, v, w, c);

			addedge(v, u, w, c);

		}

		spfa(1, n);

		int ans = 0;

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

			ans += cost[i];

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

	}

	return 0;

}