#include <bits/stdc++.h>
using namespace std;
vector<int> adj[100009];
vector<bool> visited(100009,false);
vector<int> contains(100009,0);
int ans,m;
void dfs(int source,int val){
    if(adj[source].size()==1&&source!=1&&val+contains[source]>m) //calculating how many leaf nodes are having consecutive cats>m
       { //cout<<"if fired: "<<source<<endl;
       ans--;}
    if(!contains[source])
        val=0;
    else
        val++;
    visited[source]=true;
    for(auto i:adj[source])
        if(!visited[i]){
            dfs(i,val);
        }
}

int main() {
	// your code goes here
	int n; cin>>n>>m;
	for(int i=1;i<=n;i++)
	    cin>>contains[i];
	for(int i=0;i<n-1;i++){
	    int a,b;
	    cin>>a>>b;
	    adj[a].push_back(b);
	    adj[b].push_back(a);
	}
	ans=0;
	for(int i=2;i<=n;i++)
	    if(adj[i].size()==1)   //calculating total no.of leaf nodes;
	        ans++;
	dfs(1,0);
	cout<<ans<<endl;
	return 0;
}