// Slower C++ solution:
#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;

}

// Faster C++ solution for the same problem (measured speedup: 2.691345175280976x):
#include <cstdio>

#include <cstring>

#include <algorithm>



using namespace std;



const int inf = 0x3f3f3f3f;

const int N = 10414;

const int M = 40414;



struct Edge{

	int u, v, d, c;

	int next;

}edge[M];



int cnt, head[N];

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

int op, tp, link[18014];



void add_edge(int u, int v, int d, int c);

void spfa(int n);



int main(){

	int n, m, i, u, v, d, c;

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

		cnt = 0;

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

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

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

			add_edge(u, v, d, c);

			add_edge(v, u, d, c);

		}

		spfa(n);

	}

	return 0;

}

void add_edge(int u, int v, int d, int c){

	edge[cnt].u = u;

	edge[cnt].v = v;

	edge[cnt].d = d;

	edge[cnt].c = c;

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

	head[u] = cnt++;

	return;

}

void spfa(int n){

	int i, u, v, d, c, sum;

	memset(vis, 0, sizeof(vis));

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

	memset(cost, inf, sizeof(cost));

	op = tp = 0;

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

	link[tp++] = 1;

	while(op < tp){

		u = link[op++];

		vis[u] = 0;

		for(i = head[u]; ~i; i = edge[i].next){

			v = edge[i].v, d = edge[i].d, c = edge[i].c;



			if(dis[v] > dis[u] + d || (dis[v] == dis[u] + d && cost[v] > c)){

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

				cost[v] = c;

				if(!vis[v]){

					vis[v] = 1;

					link[tp++] = v;

				}

			}

		}

	}

	sum = 0;

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

		sum += cost[i];

	}

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

	return;

}