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

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<algorithm>

#include<cstring>

#include<queue>

#include<vector>

#include<stack>

#define ls k<<1

#define rs k<<1|1

#define RG register

#define MAXN 50010

#define LL long long int

using namespace std;

const int INF=0x7fffffff;

struct node{

	int next;

	int to;

	int w;

	int c;

}t[MAXN];

int head[MAXN];

int num;

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

int n,m;

void add(int from,int to,int w,int c)

{

	t[++num].next=head[from];

	t[num].to=to;

	t[num].w=w;

	t[num].c=c;

	head[from]=num;

}

void spfa()

{

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

		{

			dis[i]=INF;vis[i]=0;cost[i]=INF;

		}

	cost[1]=dis[1]=0;vis[1]=1;

	queue<int>q;q.push(1);

	while(!q.empty())

		{

			int u=q.front();q.pop();vis[u]=0;

			for(int i=head[u];i;i=t[i].next)

				{

					int v=t[i].to;

					if(dis[v]>dis[u]+t[i].w||(dis[v]==dis[u]+t[i].w&&cost[v]>t[i].c))

						{

							dis[v]=dis[u]+t[i].w;

							cost[v]=t[i].c;

							if(!vis[v])

								{

									vis[v]=1;q.push(v);

								}

						}

				}

		}

}

int main()

{

//	freopen("1.in","r" ,stdin);

	//freopen("1.out","w",stdout);

	while(1)

		{

			scanf("%d%d",&n,&m);if(n==0&&m==0) break;

			int x,y,z,k;

			memset(head,0,sizeof(head));num=0;

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

				{

					scanf("%d%d%d%d",&x,&y,&z,&k);

					add(x,y,z,k);add(y,x,z,k);

				}

			spfa();

			int ans=0;

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

			cout<<ans<<endl;

		}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.2713075884335252x):
#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

struct node

{

    int to, w, c, next;

} edge[50005];

int head[10005], ip, cost[10005], dis[10005], n, m;

bool vis[10005];

void addedge(int u, int v, int d, int c)

{

    edge[ip].to = v;

    edge[ip].w = d;

    edge[ip].c = c;

    edge[ip].next = head[u];

    head[u] = ip++;

}

void spfa(int s)

{

    queue<int> q;

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

        cost[i] = dis[i] = INF;

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

    dis[s] = 0;

    cost[s] = 0;

    vis[s] = 1;

    q.push(s);

    while (!q.empty())

    {

        int u = q.front();

        q.pop();

        vis[u] = 0;

        for(int i = head[u];i != -1;i = edge[i].next)

        {

            int to = edge[i].to;

            int w = edge[i].w;

            if(dis[to] > dis[u] + w||(dis[to] == dis[u]+w&&cost[to] > edge[i].c))

            {

                dis[to] = dis[u] + w;

                cost[to] = edge[i].c;

                if(!vis[to])

                {

                    q.push(to);

                    vis[to] = 1;

                }

            }

        }

    }

}

int main()

{

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

    {

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

            break;

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

        ip = 0;

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

        {

            int u, v, d, c;

            scanf("%d %d %d %d", &u, &v, &d, &c);

            addedge(u, v, d, c);

            addedge(v, u, d, c);

        }

        spfa(1);

        int ans = 0;

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

            ans += cost[i];

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

    }

    return 0;

}