#include<iostream>
#include<math.h>
#include<algorithm>
#include<stdio.h>
#include<map>
#include<vector>
#include<set>
#include<iomanip>
#define F first
#define S second
#define P system("PAUSE");
#define H return 0;
#define pb push_back
using namespace std;
const long long A=100000000000000LL,N=228228;
 
vector<long long> a[N];
long long c[N],o,x,y,i,j,n,m;
 
void go(int v,int pr,int k){
	if(k>m)return;
	int ok=1;
	for(int i=0;i<a[v].size();i++)if(a[v][i]!=pr)ok=0,go(a[v][i],v,k*c[a[v][i]]+c[a[v][i]]);
	o+=ok;
}
 
int main(){
	cin>>n>>m;
	for(i=0;i<n;i++)scanf("%d",&c[i]);
	for(i=1;i<n;i++)scanf("%d%d",&x,&y),x--,y--,a[x].pb(y),a[y].pb(x);
	go(0,-1,c[0]);
	cout<<o<<"\n";
}

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