codeforces 580C(dfs)

#include<bits/stdc++.h>
#define x first
#define y second
#define pb push_back
#define IOS ios::sync_with_stdio(false);cin.tie(0);
using namespace std;
typedef unsigned long long ULL;
typedef pair<int,int> PII;
typedef pair<long,long> PLL;
typedef pair<char,char> PCC;
typedef long long LL;
const int N=5*1e5+10;
const int M=150;
const int INF=0x3f3f3f3f;
const int MOD=998244353;
int cat[N];
vector<int> g[N];
int ans,n,m;
void dfs(int u,int cnt,int father){
    if(cat[u]) cnt++;
    else cnt=0;
    if(cnt>m) return;
    if(g[u].size()==1 && u!=1){
        ans++;
        return;
    }
    for(int i=0;i<g[u].size();i++){
        if(g[u][i]==father) continue;
        dfs(g[u][i],cnt,u);
    }

}
void solve(){
    cin>>n>>m;
    for(int i=1;i<=n;i++) cin>>cat[i];
    for(int i=0;i<n-1;i++){
        int x,y;cin>>x>>y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    dfs(1,0,-1);
    cout<<ans<<endl;
}
int main(){
    IOS;
    solve();
    return 0;
}