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

#include<queue>

#include<cstdlib>

#include<cstdio>

#include<cstring>



using namespace std;

const int maxn=4e4+100;

const int inf=0x3f3f3f3f;



struct Edge{

    int next;

    int to;

    int w;

    int  c;



}G[maxn];



int inq[maxn];

int dis[maxn];

int head[maxn];

int k=0;





void adde(int v,int to,int w,int c)//加?

{

    G[k].to=to;//第k条?指向的点

    G[k].w=w;//第k条?的??

    G[k].c=c;

    G[k].next=head[v];//与第k条??同起点的上一条?的?存位置

    head[v]=k++;

}



queue<int>Q;



void spfa(int s)

{

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

        memset(inq,0,sizeof(inq));

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

        dis[s] = 0;

        inq[s] = 1;

        Q.push(s);

        while(!Q.empty())

        {

                int u = Q.front();

                Q.pop();

                inq[u]=0;

                for(int i=head[u];i!=-1;i=G[i].next)//遍?以u?起点的所有?

                {

                        int v=G[i].to;

                        if(dis[v]>dis[u]+G[i].w)

                        {

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

                                if(inq[v]==0)

                                {

                                    Q.push(v);

                                    inq[v]=1;

                                }

                        }

                }

                inq[u]=0;



        }

}



int main()

{

        int n,m;

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

        {

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

                        return 0;

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



                k=0;

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

                {

                            int a,b,c,d;

                            scanf("%d%d%d%d",&a,&b,&c,&d);

                            adde(a,b,c,d);

                            adde(b,a,c,d);

                }

                spfa(1);

                int ans=0;

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

                {

                        int mi=inf;

                        for(int j=head[i];j!=-1;j=G[j].next)

                        {

                                if(dis[G[j].to]+G[j].w==dis[i]&&G[j].c<mi)

                                        mi=G[j].c;

                        }

                        ans+=mi;

                }

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

        }

        return 0;



}

// Faster C++ solution for the same problem (measured speedup: 1.278639419866948x):
#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;

}