// 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: 1.1268839624167757x):
#include <cstdio>

#include <cstring>

#include <algorithm>

#include <queue>



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 op, tp, link[N];

int vis[N], dis[N], cost[N];

queue<int>q;



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++;

}

void spfa(int n)

{

    int v, d, c;

    while(!q.empty())q.pop();

    memset(vis, 0,sizeof(vis));

    memset(dis, inf, sizeof(dis));

    memset(cost, inf, sizeof(cost));

    dis[1]=0;

    cost[1]=0;

    vis[1]=true;

    q.push(1);

    while(!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=false;

        for(int i=head[u]; i!=-1; 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))//有多条最短路时，取花费最小的

            {

                dis[v] = dis[u] +d;

                cost[v] = c;

                if(!vis[v])

                {

                    q.push(v);

                    vis[v]=true;

                }

            }

        }

    }

    int sum = 0;

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

    	sum += cost[i];

    }

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

    return;

}