// 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: 1.26078673017205x):
#include <iostream>

#include <cstring>

const int SIZE = 10010;

const int MAX = 0x3f3f3f3f;



typedef struct Road

{

	int from;

	int to;

	int length;

	int cost;

	int next;

} Road;



int head[SIZE];

int dis[SIZE];

Road roads[SIZE * 5];

int front[SIZE];

bool visit[SIZE];



int city, road, capital;



void init()

{

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

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

	memset(visit, false, sizeof(visit));

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

	{

		dis[i] = MAX;

	}

	dis[1] = 0;

}



void dijkstra()

{

	while (true)

	{

		int pos = -1;

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

		{

			if (!visit[i] && (pos == -1 || dis[pos] > dis[i]))

			{

				pos = i;

			}

		}

		if (pos == -1)

		{

			break;

		}

		visit[pos] = true;

		for (int i = head[pos]; i != -1; i = roads[i].next)

		{

			int to = roads[i].to;

			if (dis[to] > dis[pos] + roads[i].length)

			{

				dis[to] = dis[pos] + roads[i].length;

				front[to] = i;

			}

			else if ((dis[to] == dis[pos] + roads[i].length) && front[to] != -1 && roads[i].cost < roads[front[to]].cost)

			{

				front[to] = i;

			}

		}

	}

}



int main()

{

	while (true)

	{

		std::cin >> city >> road;

		if (city == 0 && road == 0)

		{

			break;

		}

		init();

		int en = 0;

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

		{

			std::cin >> roads[en].from >> roads[en].to >> roads[en].length >> roads[en].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

			roads[en].from = roads[en - 1].to;

			roads[en].to = roads[en - 1].from;

			roads[en].length = roads[en - 1].length;

			roads[en].cost = roads[en - 1].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

		}

		dijkstra();

		int result = 0;

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

		{

			if (front[i] != -1)

			{

				result += roads[front[i]].cost;

			}

		}

		std::cout << result << std::endl;

	}

	return 0;

}