// 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: 1.2692498363181295x):
#include <stdio.h>

#include <string.h>

#include <queue>

#include <iostream>

#include <algorithm>

using namespace std;

const int maxn=10050;

const int maxe=40414;

const int INF=0x3f3f3f3f;

struct note

{

    int v;

    int d;

    int c;

    int next;

};

note edge[maxe];

int head[maxn];

int cnt;

void init()

{

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

    cnt=0;

}

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

{

    edge[cnt].v=v;

    edge[cnt].c=c;

    edge[cnt].d=d;

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

    head[u]=cnt++;

}

int cost[maxn];

int dis[maxn];

bool vis[maxn];

queue<int>q;

void spfa(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[1]=0;

    cost[1]=0;

    vis[1]=true;

    q.push(1);

    while(!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=false;

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

        {

            int v=edge[i].v;

            int val=edge[i].d;

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

            {

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

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

                if(!vis[v])

                {

                    q.push(v);

                    vis[v]=true;

                }

            }

        }

    }

}

int main()

{

    int n,m;

    int u,v,d,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,&d);

            addedge(u,v,c,d);

            addedge(v,u,c,d);

        }

        spfa(n);

        int ans=0;

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

            ans+=cost[i];

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

    }

    return 0;

}