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

#include <iostream>

#include <cstring>

#include <string>

#include <algorithm>

#include <vector>

#include <queue>

const int maxn = 10007;

const int inf =1e9;

using namespace std;

struct node{

	int to,d,c;

	node(){}

	node (int to,int d,int c):to(to),d(d),c(c){}

};

vector<node>mp[maxn];

int dis[maxn],cost[maxn],n,m,ans = 0;

void init(){

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

	{

		mp[i].clear();

		dis[i] = inf;

		cost[i]  = 0;

	}

}

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

{

	mp[u].push_back(node(v,d,c));

}

int main(){

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

	{

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

		init();

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

		{

			int u,v,d,c;

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

			add(u,v,d,c);

			add(v,u,d,c);

		}

		priority_queue<pair<int,int> >q;

		dis[1]=0;

		cost[1]=0;

		

		q.push (make_pair(-dis[1],1)) ;

		while(!q.empty())

		{

			int now = q.top().second;

			q.pop();

			for(int i=0;i<mp[now].size();i++)

			{

				int v=mp[now][i].to;

				int d=mp[now][i].d;

				int c=mp[now][i].c;

				if(dis[v]>dis[now]+d)

				{

					dis[v] = dis[now]+d;

					//ans -=cost[v];

					//cost[v] = cost[now]+c;

					//ans +=cost[v];

					q.push (make_pair(-dis[v],v));

				}

			}

		}

		ans = 0;

		for(int i=2;i<=n;i++)

		{

			int minc = inf;

			for(int j=0;j<mp[i].size();j++)

			{

				node tmp = mp[i][j];

				if(tmp.d+dis[tmp.to]==dis[i]&&minc>tmp.c)

				{

					minc = mp[i][j].c;

				}

			}

			ans += minc;

		}

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

	}

	return 0;

}


// Faster C++ solution for the same problem (measured speedup: 1.2544840281037173x):
#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;

}