// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;

struct node{

    int next,d,c;

};

const int maxn=10005;

int n,m;

int d[maxn],c[maxn];

bool vis[maxn];

void init()

{

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

        d[i]=c[i]=1e9,vis[i]=0;

}

int main()

{

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

    {

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

        init();vector<node> v[maxn];

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

        {

            int x,y,d,c;

            scanf("%d%d%d%d",&x,&y,&d,&c);

            v[x].push_back(node{y,d,c});

            v[y].push_back(node{x,d,c});

        }

        queue<int> q;

        q.push(1);

        d[1]=c[1]=0;vis[1]=1;

        while(!q.empty())

        {

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

            for(int i=0;i<v[u].size();i++)

            {

                int nx=v[u][i].next;

                if(d[nx]==d[u]+v[u][i].d&&c[nx]>v[u][i].c){

                        c[nx]=v[u][i].c;

                }

                if(d[nx]>d[u]+v[u][i].d)

                {

                    d[nx]=d[u]+v[u][i].d;

                    c[nx]=v[u][i].c;

                    if(vis[nx]) continue;

                    vis[nx]=1;

                    q.push(nx);

                }

            }

        }

        int ans=0;

        for(int i=2;i<=n;i++) ans+=c[i];

        cout<<ans<<endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.4277971245039518x):
#include <cstdio>

#include <cstdlib>

#include <iostream>

#include <cstring>

#include <cmath>

#include <ctime>

#include <algorithm>

#include <vector>

#include <set>

#include <queue>

#include <map>

#include <stack>

#include <bitset>

using namespace std;

typedef int gitype;

gitype gi () {

    gitype ret=0; char ch=getchar();

    while((ch<'0' || ch>'9') && ch!='-') ch=getchar();

    char c=ch=='-'?getchar():ch;

    while(c>='0' && c<='9') ret=ret*10+c-'0',c=getchar();

    return ch=='-'?-ret:ret;

}

const int N = 10010;

const int M = 100010;

int n,m,st[N],vis[N],dis[N],pt[M],nxt[M],w[M],c[M],cost[N],ent=0;

void link (int u,int v,int _w,int _c) {

    pt[++ent]=v; nxt[ent]=st[u]; st[u]=ent; w[ent]=_w; c[ent]=_c;

    pt[++ent]=u; nxt[ent]=st[v]; st[v]=ent; w[ent]=_w; c[ent]=_c;

}

queue<int> q;

int main () {

    while(scanf("%d%d",&n,&m)==2 && (n || m)) {

        memset(st,0,sizeof(st)); ent=0;

        int u,v,_w,_c;

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

            u=gi(); v=gi(); _w=gi(); _c=gi(); link(u,v,_w,_c);

        }

        for(int i=1;i<=n;i+=1) dis[i]=1e9 + 5;

        dis[1]=0; q.push(1);

        while(!q.empty()) {

            int r=q.front(); q.pop(); vis[r]=false;

            for(int i=st[r];i;i=nxt[i]) {

                if(dis[pt[i]] > dis[r]+w[i]) {

                    dis[pt[i]] = dis[r]+w[i]; cost[pt[i]] = c[i];

                    if(!vis[pt[i]]) {

                        vis[pt[i]] = true; q.push(pt[i]);

                    }

                } else if(dis[pt[i]] == dis[r]+w[i]) {

                    cost[pt[i]] = min(cost[pt[i]], c[i]);

                }

            }

        }

        int ans = 0;

        for(int i=2;i<=n;i+=1) ans += cost[i];

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

    }

    return 0;

}