// 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: 3.3839838214670386x):
#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;

}