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

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<queue>

#include<vector>

#include<stack>

#define ls k<<1

#define rs k<<1|1

#define RG register

#define MAXN 50010

#define LL long long int

using namespace std;

const int INF=0x7fffffff;

struct node{

	int next;

	int to;

	int w;

	int c;

}t[MAXN];

int head[MAXN];

int num;

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

int n,m;

void add(int from,int to,int w,int c)

{

	t[++num].next=head[from];

	t[num].to=to;

	t[num].w=w;

	t[num].c=c;

	head[from]=num;

}

void spfa()

{

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

		{

			dis[i]=INF;vis[i]=0;cost[i]=INF;

		}

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

	queue<int>q;q.push(1);

	while(!q.empty())

		{

			int u=q.front();q.pop();vis[u]=0;

			for(int i=head[u];i;i=t[i].next)

				{

					int v=t[i].to;

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

						{

							dis[v]=dis[u]+t[i].w;

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

							if(!vis[v])

								{

									vis[v]=1;q.push(v);

								}

						}

				}

		}

}

int main()

{

//	freopen("1.in","r" ,stdin);

	//freopen("1.out","w",stdout);

	while(1)

		{

			scanf("%d%d",&n,&m);if(n==0&&m==0) break;

			int x,y,z,k;

			memset(head,0,sizeof(head));num=0;

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

				{

					scanf("%d%d%d%d",&x,&y,&z,&k);

					add(x,y,z,k);add(y,x,z,k);

				}

			spfa();

			int ans=0;

			for(int i=1;i<=n;i++) ans+=cost[i];

			cout<<ans<<endl;

		}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1962904979158773x):
    #include <stdio.h>

    #include <string.h>

    #include <queue>

    #include <iostream>

    #include <algorithm>

    using namespace std;

    const int maxn=10050;

    const int maxe=2005000;

    const int INF=1e9;

    struct note

    {

        int to;

        int w;

        int c;

        int next;

    };

    note 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];

    int dis[maxn];

    bool vis[maxn];

    queue<int>q;

    void spfa(int s,int n)

    {

        while(!q.empty())q.pop();

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

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

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

        dis[s]=0;

        cost[s]=0;

        vis[s]=true;

        q.push(s);

        while(!q.empty())

        {

            int u=q.front();

            q.pop();

            vis[u]=false;

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

            {

                int to=edge[i].to;

                int val=edge[i].w;

                if(dis[to]>dis[u]+val||(dis[to]==dis[u]+val&&cost[to]>edge[i].c))//有多条最短路时，取花费最小的

                {

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

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

                    if(!vis[to])

                    {

                        q.push(to);

                        vis[to]=true;

                    }

                }

            }

        }

    }

    int main()

    {

        int n,m;

        int u,v,w,c;

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

        {

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

            init();

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

            {

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

                addedge(u,v,c,w);

                addedge(v,u,c,w);

            }

            spfa(1,n);

            int ans=0;

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

                ans+=cost[i];

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

        }

        return 0;

    }