// 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: 1.2675254265117206x):
#include <iostream>

#include <stdio.h>

#include <string.h>

#include <queue>

using namespace std;

const int maxn=10050,maxm=20050,inf=0x3f3f3f3f;

struct Edge

{

    int to,next,dis,cos ;

}edge[maxm*2];

struct Pair

{

    int D,V,C;

    Pair(){;}

    Pair(int d,int c,int v)

    {

        D=d,V=v,C=c;

    }

    friend bool operator <(const Pair a,const Pair b)

    {

        if(a.D!=b.D)

        return a.D>b.D;

        else return a.C>b.C;

    }

};

int tot,head[maxn],dist[maxn],cost[maxn];

bool vis[maxn];

void init()

{

    tot=0;

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

}

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

{

    edge[tot].to=v;

    edge[tot].dis=d;

    edge[tot].cos=c;

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

    head[u]=tot++;

}

int dijstra(int start)

{

    memset(vis,false,sizeof(vis));

    memset(dist,inf,sizeof(dist));

    int ans=0;

    dist[start]=0;

   // vis[start]=true;

    priority_queue<Pair>que;

    que.push(Pair(0,0,start));

    while(!que.empty())

    {

        Pair now=que.top();

        que.pop();

        if(vis[now.V])

            continue;

        vis[now.V]=true;

        ans+=now.C;

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

        {

            int to=edge[i].to;

            que.push(Pair(now.D+edge[i].dis,edge[i].cos,to));

        }

    }

    return ans;

}

int main()

{

    int u,v,d,c;

    int n,m;

    while(scanf("%d%d",&n,&m)!=-1)

    {

        init();

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

        for(int 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);

        }

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

    }

    return 0;

}