// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <cstdlib>

#include <algorithm>

#include <cstring>

#include <vector>

#include <cmath>

#include <queue>



using namespace std;

#define Fill(a, b) memset(a, b, sizeof(a))

#define Debug(x) cout<<#x<<"="<<(x)<<endl;

typedef pair<int, int> P;

const int inf = 0x1f1f1f1f;

const int max_n = 10010;

struct edge

{

    int from, to, cost, fee;

};

int n, ans;

//vector<int> g fee[max_n];

int d[max_n], pre[max_n];

vector<edge> G[max_n];

void dijkstra(int s);

vector<int> get_path(int t);

int main()

{

    int i = 0, j = 0, k = 0;

    int m, a, b, p, q;

    edge ei;

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

    {

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

            break;

        ans = 0;

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

            G[i].clear();

        for(i = 0; i < m; i++)

        {

            scanf("%d %d %d %d", &a, &b, &p, &q);

            ei.from = a;

            ei.to = b;

            ei.cost = p;

            ei.fee = q;

            G[a].push_back(ei);

            ei.from = b;

            ei.to = a;

            G[b].push_back(ei);

        }

        dijkstra(1);



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

        /*

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

            cout << pre[i] << " ";

        cout << endl;

        */

    }



    return 0;

}

void dijkstra(int s)

{

    int i, j, u, v;

    priority_queue<P, vector<P>, greater<P> > que;

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

    {

        d[i] = inf;

    }

    Fill(pre, -1);

    d[s] = 0;

    que.push(P(0, s));

    while(!que.empty())

    {

        P pa = que.top();

        que.pop();

        v = pa.second;

        if(d[v] < pa.first)

            continue;

        edge es;

        for(i = 0; i < G[v].size(); i++)

        {

            es = G[v][i];

            if(d[es.to] > d[es.from]+es.cost)

            {

                if(d[es.to]!=inf)

                    ans -= pre[es.to];

                d[es.to] = d[es.from]+es.cost;

                ans += es.fee;

                pre[es.to] = es.fee;

                que.push(P(d[es.to], es.to));

            }

            else if((d[es.to]==d[es.from]+es.cost)&&(pre[es.to]>es.fee))

            {

                ans = ans - pre[es.to] + es.fee;

                pre[es.to] = es.fee;

            }

        }

    }

}

// Faster C++ solution for the same problem (measured speedup: 1.0956962498850689x):
#include <cstdio>

#include <queue>

#include <vector>

#include <algorithm>



using namespace std;

const int INF = 0x3f3f3f3f;



const int maxn = 10240;



struct edge {

	int to, dis, cost;

	edge(int t, int d, int c) : to(t), dis(d), cost(c) {}

};





typedef pair<int, int> p;

priority_queue<p, vector<p>, greater<p> > q;

vector<edge> g[maxn];



int N, M;



void read_in() {

	//scanf("%d%d", &N, &M);

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

		g[i].clear();



	int from, to, dis, cost;

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

		scanf("%d%d%d%d", &from, &to, &dis, &cost);

		g[from].push_back(edge(to, dis, cost));

		g[to].push_back(edge(from, dis, cost));

	}

}



int solve() {

	q.push(p(0, 1));



	const int INF = 0x7777777;

	int d[maxn];



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

		d[i] = INF;

	d[1] = 0;



	while( !q.empty() ) {

		p t = q.top();

		q.pop();



		int to = t.second, dis = t.first;

        if(d[to] < dis) continue;

		for(unsigned int i = 0; i < g[to].size(); i++) {

			edge To = g[to][i];

			if(d[To.to] > d[to] + To.dis)

				d[To.to] = d[to] + To.dis,

				q.push(p(d[To.to], To.to));

		}

	}

	//show(d);

    int ans = 0;



    for(int i = 2; i <= N; i++) {

        int tmp = INF;



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

            edge e = g[i][j];

            if(d[e.to] + e.dis == d[i] and e.cost < tmp)

                tmp = e.cost;

        }

        ans += tmp;

    }



    return ans;

}



int main() {

	while(scanf("%d %d", &N, &M) and N) {

		read_in();

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

	}

	return 0;

}