#pragma warning (disable : 4996)
#include<iostream>
#include<string> 
#include<stack>
#include<vector>
#include<cmath>
#include<algorithm>
#include<queue>
#include<sstream>
#include<ctype.h>
#include<memory.h>
#include<stdlib.h>
#include<fstream>
#include<set>
#include<stdio.h>
#include<bitset>
#include<map>
using namespace std;


int vis[111111];
int d[111111];
int power[111111];
vector<int> v[111111];
int cnt;
int n, m;

void bfs(int x){
    queue<int> q;
    q.push(x);
    vis[x] = 1;
    if (power[x] == 1)
        d[x] = 1;
    while (!q.empty()){
        int n = q.front();
        q.pop();
        for (int i = 0; i < (int)v[n].size(); i++){
            int x = v[n][i];
            if (!vis[x]){
                if (power[x] && power[n])
                    d[x] = d[n] + 1;
                vis[x] = 1;
                if (d[x] <= m){
                    q.push(x);
                    if (v[x].size() == 1)
                        cnt++;
                }
            }
        }
    }
}

int main(){
   // freopen("input.in", "r", stdin);
    scanf("%d%d", &n, &m);

    for (int i = 0; i < n; i++)
        scanf("%d", &power[i]);
    for (int i = 0; i <n-1; i++){
        int a, b;
        scanf("%d%d", &a, &b);
        --a, --b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    bfs(0);
    printf("%d", cnt);

    return 0;
}