'''
Don't Copy This Code, CopyRight . [email protected] © 2022-2023 :)
'''
import sys
import threading
sys.setrecursionlimit(2147483647)
input = sys.stdin.readline
def print(*args, end='\n', sep=' ') -> None:
sys.stdout.write(sep.join(map(str, args)) + end)
def dfs(node , visited , c):
global graph, x
if(x[node - 1]):c += 1
else:c = 0
if(c > m):return 0
ans = 0
for i in graph[node]:
if(i != visited):
ans += dfs(i , node , c)
if(node != 1 and len(graph[node]) == 1):return 1
return ans
def Solve():
global x, m, ans, graph
n, m = map(int, input().split())
x = list(map(int, input().split()))
ans = 0
graph = dict()
for i in range(n-1):
a, b = map(int, input().split())
if a not in graph.keys():
graph[a] = set()
if b not in graph.keys():
graph[b] = set()
graph[a].add(b)
graph[b].add(a)
ans = dfs(1, -1, 0)
print(ans)
if __name__ == "__main__":
threading.stack_size(10**8)
threading.Thread(target=Solve).start()#include <bits/stdc++.h>
#define pb push_back
#define sz(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define ll long long
using namespace std;
const int MOD = 1e9 + 7;
const int N = 2e5+6;
int n,m;
vector<int>g[N];
int a[N];
int dfs(int u,int c,int p){
if(c > m)return 0;
if(sz(g[u]) == 1 && u != 1)return 1;
int ret = 0;
for(auto v : g[u]){
if(v == p)continue;
if(a[v] == 1){
ret += dfs(v,c+1,u);
}else{
ret += dfs(v,0,u);
}
}
return ret;
}
void solve(int tc){
scanf("%d %d",&n,&m);
for(int i = 1;i<=n;i++)scanf("%d",&a[i]);
for(int i = 1,u,v;i<n;i++)scanf("%d %d",&u,&v),g[u].pb(v),g[v].pb(u);
printf("%d\n",dfs(1,a[1],0));
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tc = 1;
//cin>>tc;
//scanf("%d",&tc);
for(int i = 1;i<=tc;i++)
solve(i);
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