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

#include<cstring>

#include<queue>

#include<vector>

using namespace std;

#define INF 1000000000

#define pb push_back

#define maxn 10001

struct Edge{

	int from, to, dist, cost;

};

struct HeapNode{

	int d, u, c;

	bool operator < (const HeapNode& a)const{

		if(d==a.d)	return c>a.c;

		return d>a.d;

	}

};

inline void IN(int& x){

	x=0;

	char c=getchar();

	while(c<48 || c>57)	c=getchar();

	while(c>=48 && c<=57){

		x=x*10+c-48;

		c=getchar();

	}

}

int n, m;

vector<Edge> edges;

vector<int> G[maxn];

vector<int> V[maxn];

bool done[maxn];

int d[maxn], p[maxn], c[maxn];

int ans;

void init(){

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

		G[i].clear();

		V[i].clear();

	}

	edges.clear();

}

void add(int from, int to, int dist, int cost){

	edges.pb((Edge){from, to, dist, cost});

	m = edges.size();

	G[from].pb(m-1);

	V[from].pb(cost);

}

void dijkstra(int s){

	ans=0;

	priority_queue<HeapNode> Q;

	for(int i=1; i<=n; i++)	d[i]=INF;

	for(int i=1; i<=n; i++)	c[i]=INF;

	d[s]=0;

	c[s]=0;

	memset(done, 0, sizeof(done));

	Q.push((HeapNode){0,s,0});

	while(!Q.empty()){

		HeapNode x = Q.top(); Q.pop();

		int u=x.u;

		if(done[u])	continue;

		done[u]=1;

		ans += c[u];

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

			Edge& e = edges[G[u][i]];

			if(d[e.to]>d[u]+e.dist || (d[e.to]==d[u]+e.dist && c[e.to]>V[u][i])){

				d[e.to] = d[u]+e.dist;

				p[e.to] = G[u][i];

				c[e.to] = V[u][i];

				Q.push((HeapNode){d[e.to],e.to,c[e.to]});

			}

		}

	}

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

}

int k;

int main(){

	while(1){

		IN(n); IN(k);

		if(!n && (!k))	break;

		int a, b, c, d;

		init();

		while(k--){

			IN(a); IN(b); IN(c); IN(d);

			add(a, b, c, d);

			add(b, a, c, d);

		}

		dijkstra(1);

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1943079252820572x):
#include<stdio.h>

#include<string.h>  

#include<math.h>  

  

//#include<map>   

//#include<set>

#include<deque>  

#include<queue>  

#include<stack>  

#include<bitset> 

#include<string>  

#include<iostream>  

#include<algorithm>  

using namespace std;  

  

#define ll long long  

#define INF 0x3f3f3f3f  

#define mod 1000000

#define clean(a,b) memset(a,b,sizeof(a))// 水印 



struct node{

	int to,next,dis,cost;

}edge[40100];

int head[10100];

int dis[10100],cost[10100];

bool vst[10100];

int n,m,k;



void spfa(int x)

{

	clean(dis,INF);

	clean(cost,INF);

	clean(vst,0);

	queue<int> q;

	dis[x]=0;

	cost[x]=0;

	q.push(x);

	while(!q.empty())

	{

		x=q.front();q.pop();

		vst[x]=0;

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

		{

			node b=edge[i];

			if(dis[b.to]>dis[x]+b.dis)

			{

				if(!vst[b.to])

				{

					vst[b.to]=1;

					q.push(b.to);

				}

				dis[b.to]=dis[x]+b.dis;

				cost[b.to]=b.cost;

			}

			else if(dis[b.to]==dis[x]+b.dis)

			{

				if(cost[b.to]>b.cost)

					cost[b.to]=b.cost;

			}

		}

	}

}



void add(int a,int b,int dis,int cost)

{

	edge[k].to=b;

	edge[k].dis=dis;

	edge[k].cost=cost;

	edge[k].next=head[a];

	head[a]=k;

	k++;

}



int main()

{

	while(cin>>n>>m&&n!=0||m!=0)

	{

		clean(head,-1);

		k=0;

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

		{

			int a,b,d,c;

			cin>>a>>b>>d>>c;

			add(a,b,d,c);

			add(b,a,d,c);

		}

		spfa(1);

		ll res=0;

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

			res=res+cost[i];

		cout<<res<<endl;

	}

}