// 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: 1.1369375234149406x):
#include <cstdio>

#include <iostream>

#include <cstring>

#include <string>

#include <algorithm>

#include <vector>

#include <queue>

const int maxn = 10007;

const int inf =1e9;

using namespace std;

struct node{

	int to,d,c;

	node(){}

	node (int to,int d,int c):to(to),d(d),c(c){}

};

vector<node>mp[maxn];

int dis[maxn],cost[maxn],n,m,ans = 0;

void init(){

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

	{

		mp[i].clear();

		dis[i] = inf;

		cost[i]  = 0;

	}

}

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

{

	mp[u].push_back(node(v,d,c));

}

int main(){

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

	{

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

		init();

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

		{

			int u,v,d,c;

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

			add(u,v,d,c);

			add(v,u,d,c);

		}

		priority_queue<pair<int,int> >q;

		dis[1]=0;

		cost[1]=0;

		

		q.push (make_pair(-dis[1],1)) ;

		while(!q.empty())

		{

			int now = q.top().second;

			q.pop();

			for(int i=0;i<mp[now].size();i++)

			{

				int v=mp[now][i].to;

				int d=mp[now][i].d;

				int c=mp[now][i].c;

				if(dis[v]>dis[now]+d)

				{

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

					//ans -=cost[v];

					//cost[v] = cost[now]+c;

					//ans +=cost[v];

					q.push (make_pair(-dis[v],v));

				}

			}

		}

		ans = 0;

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

		{

			int minc = inf;

			for(int j=0;j<mp[i].size();j++)

			{

				node tmp = mp[i][j];

				if(tmp.d+dis[tmp.to]==dis[i]&&minc>tmp.c)

				{

					minc = mp[i][j].c;

				}

			}

			ans += minc;

		}

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

	}

	return 0;

}