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

#include <cstring>

#include <queue>

#define inf 0x3f3f3f3f

#define maxm 10005

#define maxn 40005



using namespace std;



int m,n;

long long edgenum,head[maxm],dis[maxm],num[maxm],ans;

bool vis[maxm];



struct node

{

    int from,to,len,cost,next;

}edge[maxn];



void init()

{

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

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

    memset(dis,inf,sizeof(dis));

    memset(num,inf,sizeof(num));

    edgenum=0;

}



void add(int u,int v,int len,int cost)

{

    node tp={u,v,len,cost,head[u]};

    edge[edgenum]=tp;

    head[u]=edgenum++;

}



long long SPFA(int st)

{

     queue<int> q;

     q.push(st);

     vis[st]=1;

     dis[st]=0;

     num[st]=0;

     ans=0;

     while(!q.empty())

     {

          int tmp=q.front();

          q.pop();

          vis[tmp]=0;

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

          {

                if((dis[edge[i].to]>dis[tmp]+edge[i].len)||((dis[edge[i].to]==dis[tmp]+edge[i].len)&&(num[edge[i].to]>edge[i].cost)))

                {

                    dis[edge[i].to]=dis[tmp]+edge[i].len;

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

                    if(!vis[edge[i].to])

                    {

                        q.push(edge[i].to);

                        vis[edge[i].to]=1;

                    }

                }

          }

     }

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

        ans+=num[i];

     return ans;

}



int main()

{

    int u,v,len,cost;

    while(cin>>m>>n&&m)

    {

        init();

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

        {

            cin>>u>>v>>len>>cost;

            add(u,v,len,cost);

            add(v,u,len,cost);

        }

        cout<<SPFA(1)<<endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.2160081459020045x):
#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;

}