#include<bits/stdc++.h>

using namespace std;

const int  N=1e5+5,
        INF=1e9+7;

int  ans;

int  n, m;

vector<int >a[N];

bool usd[N], c[N];

void dfs(int  v, int  sum=0)
{
    usd[v]=true;
    sum+=c[v];

    if (sum>m) return;
    if (!c[v]) sum=0;

    if (a[v].size()==1) ans++;

    for (int  i=0; i<a[v].size(); ++i){
        int  to=a[v][i];
            if (!usd[to])
                dfs(to, sum);
    }
}
main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    cin>>n>>m;
    for (int  i=1; i<=n; ++i){
        cin>>c[i];
    }
    for (int  i=1; i<n; ++i){
        int  x, y;

        cin>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }

    dfs(1);

    cout<<ans;
}