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

using namespace std;



typedef long long ll;

const int N = 10005;

const int M = 1000000007;



int n, m;

typedef int wtype;

struct Edge { int v; wtype d, c; };

vector<Edge> e[N];

wtype dist[N], cost[N];

int pre[N];

bool vis[N];

int SPFA(int src) {

  memset(dist, 0x3f, sizeof(dist)); dist[src] = 0;

  memset(cost, 0x3f, sizeof(cost)); cost[src] = 0;

  memset(vis, 0, sizeof(vis)); vis[src] = true;

  stack<int> que; que.push(src);

  while (!que.empty()) {

    int u = que.top(); que.pop();

    vis[u] = false;

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

      int v = e[u][i].v; wtype d = e[u][i].d, c = e[u][i].c;

      if (dist[v] > dist[u] + d || (dist[v] == dist[u] + d && cost[v] != 0x3f3f3f3f && cost[v] > c)) {

        dist[v] = dist[u] + d; cost[v] = c;

        if (!vis[v]) { vis[v] = true; que.push(v); }

      }

    }

  }

  int ret = 0;

  for (int i = 1; i <= n; i++) { ret += cost[i]; }

  return ret;

}



int main() {

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

    for (int i = 1; i <= n; i++) { e[i].clear(); }

    for (int i = 0, u, v, d, c; i < m; i++) {

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

      e[u].push_back((Edge) {v, d, c});

      e[v].push_back((Edge) {u, d, c});

    }

    printf("%d\n", SPFA(1));

  }

}

// Faster C++ solution for the same problem (measured speedup: 1.2076300840525762x):
#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<queue>

#define IL inline

#define RG register

#define inf 0x3f3f3f3f

#define LL long long

#define N 10005

#define M 20005

using namespace std;

IL int gi()

{

	RG int res=0,s=1;RG char ch;

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

	if(ch=='-') s=-1,ch=getchar();

	for(;ch>='0'&&ch<='9';ch=getchar()) res=10*res+ch-48;

	return res*s;

}

int n,m,head[N],edge[2*M][5],num=-1;

int dis[N],flag[N],ans=0,a[N];

struct node

{

	int d,v;

	node(RG int dd=0,RG int vv=0){d=dd,v=vv;}

	bool operator < (const node &o) const{

		return v>o.v;

	}

};

priority_queue<node>heap;

IL void adde(RG int u,RG int v,RG int d,RG int c)

{

	edge[++num][0]=v;edge[num][1]=head[u];head[u]=num;edge[num][2]=d,edge[num][3]=c,edge[num][4]=0;

	edge[++num][0]=u;edge[num][1]=head[v];head[v]=num;edge[num][2]=d,edge[num][3]=c,edge[num][4]=0;

}

IL void init(){

	memset(head,-1,sizeof(head)); num=-1; ans=0;

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

	memset(flag,0,sizeof(flag));

}

IL int cmp(RG int x,RG int y){return dis[x]<dis[y];}

IL void work1()

{

	RG int p;

	dis[1]=0; heap.push(node(1,0));

	while(!heap.empty())

		{

			p=heap.top().d; heap.pop();

			while(flag[p]&&!heap.empty()) p=heap.top().d,heap.pop();

			if(flag[p]) break; flag[p]=1;

			for(RG int i=head[p];i!=-1;i=edge[i][1]){

				if(dis[edge[i][0]]>dis[p]+edge[i][2]){

					dis[edge[i][0]]=dis[p]+edge[i][2];

					heap.push(node(edge[i][0],dis[edge[i][0]]));

				}

			}

		}

	RG int mn;

	for(RG int i=1;i<=n;++i) a[i]=i;

	sort(a+1,a+n+1,cmp);

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

		{

			mn=inf;

			for(RG int j=head[i];j!=-1;j=edge[j][1])

				{

					if(dis[i]==dis[edge[j][0]]+edge[j][2])

						mn=min(mn,edge[j][3]);

				}

			ans+=mn;

		}

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

}

int main()

{

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

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

	RG int u,v,d,c;

	while(true)

		{

			n=gi(),m=gi(); if(!n&&!m) break; init();

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

				u=gi(),v=gi(),d=gi(),c=gi(),adde(u,v,d,c);

			work1();

		}

	//fclose(stdin);fclose(stdout);

	return 0;

}