// Slower C++ solution:
#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;

}


// Faster C++ solution for the same problem (measured speedup: 1.1092998442180197x):
#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

struct node

{

    int to, w, c, next;

} edge[50005];

int head[10005], ip, cost[10005], dis[10005], n, m;

bool vis[10005];

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

{

    edge[ip].to = v;

    edge[ip].w = d;

    edge[ip].c = c;

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

    head[u] = ip++;

}

void spfa(int s)

{

    queue<int> q;

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

        cost[i] = dis[i] = INF;

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

    dis[s] = 0;

    cost[s] = 0;

    vis[s] = 1;

    q.push(s);

    while (!q.empty())

    {

        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;

            int w = edge[i].w;

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

            {

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

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

                if(!vis[to])

                {

                    q.push(to);

                    vis[to] = 1;

                }

            }

        }

    }

}

int main()

{

    while (scanf("%d %d", &n, &m) != EOF)

    {

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

            break;

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

        ip = 0;

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

        {

            int u, v, d, c;

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

            addedge(u, v, d, c);

            addedge(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;

}