// iee
#include <bits/stdc++.h>
#define int long long
using ll = long long;
using ull = unsigned long long;
using pii = std::pair<int,int>;
using db = double;
using ld = long double;
#define py puts("YES")
#define pn puts("NO")
#define pf puts("-1")
#define hh puts("")
#define fi first
#define se second
#define mkp make_pair
#define re =RD()
#define rd RD()
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define eb emplace_back
#define ep emplace
#define ci const int
#define vi vector<int>
#define fn for(int i=1;i<=n;++i)
#define rep(stO,a,b) for(int stO=(a);stO<=(b);stO++)
#define Rep(stO,a,b) for(int stO=(a);stO<(b);stO++)
#define per(Orz,a,b) for(int Orz=(a);Orz>=(b);Orz--)
#define ina int n,a[N];
#define rna n=RD();fn a[i]=RD();
using namespace std;
void big(int &x,int y){if(y>x)x=y;}void sml(int &x,int y){if(y<x)x=y;}
int qpow(int a, int b, int p) { int res = 1 % p; while (b) { if (b % 2) res = 1ll * res * a % p; a = 1ll * a * a % p; b /= 2; } return res; }
int RD() { int x = 0, f = 1, ch = getchar(); while (!isdigit(ch)) { if (ch == '-') f = -1; ch = getchar(); } while (isdigit(ch)) { x = x * 10 + (ch - '0'); ch = getchar(); } return x * f; }
//ci p = 998244353 1000000007; int fac[N], inv[N], ifac[N]; int binom(int x, int y, int MOD = p) { if (x < y) return 0; return 1ll * fac[x] * ifac[y] % p * ifac[x - y] % p; } void init(int LIM = N - 1, int MOD = p) { fac[0] = ifac[0] = inv[1] = 1; rep(i, 1, LIM) fac[i] = 1ll * fac[i - 1] * i % MOD; rep(i, 2, LIM) inv[i] = 1ll * (MOD - MOD / i) * inv[MOD % i] % MOD; rep(i, 1, LIM) ifac[i] = 1ll * ifac[i - 1] * inv[i] % MOD; }
void work(int);
signed main() { int CASINPUT = 1;
string op = R"(
)";if (op.size() == 19) cin >> CASINPUT; rep(CUR, 1, CASINPUT) work(CUR); }
ci N = 2e5 + 5;
vi e[N];
int h[N], n, k;
int ans;
int dfs(int u, int pr = 0) {
int sum = h[u];
vi v;
for (int to: e[u]) {
if (to == pr) continue;
v.pb(dfs(to, u));
}
sort(all(v),greater<int>());
sum += accumulate(all(v),0ll);
Rep(i,0,v.size()) {
if(sum <= k)break;
ans++;
sum -= v[i];
}
return sum;
}
void work(int CASE) {
n re, k re;
rep(i,1,n) h[i] re;
rep(i, 1, n - 1) {
int u re, v re;
e[u].pb(v), e[v].pb(u);
}
dfs(1);
cout << ans;
}
