// 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: 1.364122203935354x):
#include <cstdio>

#include <cstdlib>

#include <iostream>

#include <cstring>

#include <cmath>

#include <ctime>

#include <algorithm>

#include <vector>

#include <set>

#include <queue>

#include <map>

#include <stack>

#include <bitset>

using namespace std;

typedef int gitype;

gitype gi () {

    gitype ret=0; char ch=getchar();

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

    char c=ch=='-'?getchar():ch;

    while(c>='0' && c<='9') ret=ret*10+c-'0',c=getchar();

    return ch=='-'?-ret:ret;

}

const int N = 10010;

const int M = 100010;

int n,m,st[N],vis[N],dis[N],pt[M],nxt[M],w[M],c[M],cost[N],ent=0;

void link (int u,int v,int _w,int _c) {

    pt[++ent]=v; nxt[ent]=st[u]; st[u]=ent; w[ent]=_w; c[ent]=_c;

    pt[++ent]=u; nxt[ent]=st[v]; st[v]=ent; w[ent]=_w; c[ent]=_c;

}

queue<int> q;

int main () {

    while(scanf("%d%d",&n,&m)==2 && (n || m)) {

        memset(st,0,sizeof(st)); ent=0;

        int u,v,_w,_c;

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

            u=gi(); v=gi(); _w=gi(); _c=gi(); link(u,v,_w,_c);

        }

        for(int i=1;i<=n;i+=1) dis[i]=1e9 + 5;

        dis[1]=0; q.push(1);

        while(!q.empty()) {

            int r=q.front(); q.pop(); vis[r]=false;

            for(int i=st[r];i;i=nxt[i]) {

                if(dis[pt[i]] > dis[r]+w[i]) {

                    dis[pt[i]] = dis[r]+w[i]; cost[pt[i]] = c[i];

                    if(!vis[pt[i]]) {

                        vis[pt[i]] = true; q.push(pt[i]);

                    }

                } else if(dis[pt[i]] == dis[r]+w[i]) {

                    cost[pt[i]] = min(cost[pt[i]], c[i]);

                }

            }

        }

        int ans = 0;

        for(int i=2;i<=n;i+=1) ans += cost[i];

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

    }

    return 0;

}