#include <bits/stdc++.h>
using namespace std;
//#define int unsigned long long
//#define vector deque
#define int long long
#define tt true
#define ff false
#define F first
#define S second
#define endl '\n'
#define ins insert
#define pb push_back
#define pf push_front
#define lb lower_bound
#define ub upper_bound
#define yes cout << "YES" << endl
#define no cout << "NO" << endl
#define srt(p) sort(p.begin() , p.end())
#define rvr(p) reverse(p.begin() , p.end())
const int MAX = 3e5, MOD = 1e9 + 7;
int G[MAX + 1];
vector<int> vts1;
vector<bool> vts(MAX);
/*
int pw(int a, int b) {
int ans = 1;
while(b > 0) {
if(b % 2 == 1) {
ans *= a;
}
a *= a;
b /= 2;
}
return ans;
}
/*
int factorial(int n) {
if(n == 0 || n == 1) return 1;
return n * factorial(n - 1);
}
bool is_prime(int n) {
if(n == 1 or n == 0) return false;
if(n == 2) return true;
if(n % 2 == 0) return false;
for(int i = 3; i <= sqrt(n); i+=2) {
if(n % i == 0) return false;
}
return true;
}
void sieve() {
vts[0] = tt;
vts[1] = tt;
for(int i = 2; i <= sqrt(MAX); i++) {
if(vts[i] == ff) {
for(int j = i * i; j <= MAX; j += i) {
vts[j] = tt;
}
}
}
for(int i = 0; i < MAX; i++) {
if(!vts[i]) {
vts1.push_back(i);
}
}
}
vector<int> sieve_massiv() {
int n = MAX;
vector<int> ans;
vector<bool> ans2(MAX, true);
ans2[0] = false;
ans2[1] = false;
for(int i = 2; i <= n; i++) {
if(ans2[i]) {
ans.push_back(i);
for(int j = i * i; j <= n; j += i) {
ans2[j] = false;
}
}
}
return ans;
}
vector<int> divisors(int n) {
vector<int> divi;
for(int i = 1; i <= sqrt(n); i++) {
if(n % i == 0) {
divi.push_back(i);
if(i != n / i) divi.push_back(n / i);
}
}
sort(divi.begin(), divi.end());
return divi;
}
int phi(int n) {
int ans = n;
for(int i = 2; i * i <= n; i++) {
if(n % i == 0) {
while(n % i == 0) {
n /= i;
}
ans -= ans / i;
}
}
if(n > 1) {
ans -= ans / n;
}
return ans;
}
string binaryaplsub(string a, string b) {
int n = a.size(), m = b.size();
int maxi = max(n, m);
string ans = "";
int yadda = 0;
while(a.size() < maxi) {
a = "0" + a;
}
while(b.size() < maxi) {
b = "0" + b;
}
for(int i = maxi - 1; i >= 0; i--) {
int A = a[i] - '0';
int B = b[i] - '0';
int sum = A + B + yadda;
if(sum == 0) {
ans = "0" + ans;
yadda = 0;
}
else if(sum == 1) {
ans = "1" + ans;
yadda = 0;
}
else if(sum == 2) {
ans = "0" + ans;
yadda = 1;
}
else if(sum == 3) {
ans = "1" + ans;
yadda = 1;
}
}
if(yadda != 0) ans = "1" + ans;
return ans;
}
int pfc(int n) {
int cnt = 0;
for(int i = 2; i <= sqrt(n); i++) {
if((int64_t)i * i > n) break;
if(n % i == 0) {
while(n % i == 0) {
n /= i;
cnt++;
}
}
}
if(n > 1) cnt++;
return cnt;
}
int primecntInterval(int a, int b) {
int n = b - a + 1;
int n1 = sqrt(b) + 1;
vector<bool> isPrime(n, true);
if(a == 0) {
isPrime[0] = false;
if(n > 1) isPrime[1] = false;
}
else if(a == 1) {
isPrime[0] = false;
}
vector<bool> vtt(n1 + 1, false);
vector<int> vt;
for(int i = 2; i <= n1; i++) {
if(!vtt[i]) {
vt.push_back(i);
for(int j = i * i; j <= n1; j += i) {
vtt[j] = true;
}
}
}
for(int i = 0; i < vt.size(); i++) {
int start = max(vt[i] * vt[i], ((a + vt[i] - 1) / vt[i]) * vt[i]);
for(int j = start; j <= b; j += vt[i]) {
isPrime[j - a] = false;
}
}
int smd = 0;
for(int i = 0; i < n; i++) {
if(isPrime[i]) {
smd++;
}
}
return smd;
}
void pppp() {
vector<int> phi_arr(MAX + 1);
for(int i = 0; i <= MAX; i++) phi_arr[i] = i;
for(int i = 2; i <= MAX; i++) {
if(phi_arr[i] == i) {
for(int j = i; j <= MAX; j += i) {
phi_arr[j] -= phi_arr[j] / i;
}
}
}
for(int i = 1; i <= MAX; i++) {
for(int j = i; j <= MAX; j += i) {
G[j] += i * phi_arr[j / i];
}
}
for(int i = 1; i <= MAX; i++) {
G[i] += G[i - 1] - i;
}
}
string bitwise(int n) {
string s = "";
while(n > 0) {
int qaliq = n % 2;
if(qaliq == 1) s += '1';
else s += '0';
n /= 2;
}
reverse(s.begin(), s.end());
return s;
}
bool is_palindrome(string s) {
string t = s;
reverse(t.begin(), t.end());
return t == s;
}
//vector<int> vts1 = sieve_massiv();
/* ------------FOR DP----------
int n;
vector<int> vt;
int dp[MAX];
int dpp(int i){
if(dp[i] != 0) return dp[i];
int best = 1;
for(int j = 0; j < i; ++j){
if(vt[j] <= vt[i]){
best = max(best , dpp(j) + 1);
}
}
return dp[i] = best;
}
*/
bool ok1(vector<int> wreath , int k) {
for(int i = 0; i < wreath.size(); ++ i) {
if(wreath[i] > k) {
return false;
}
}
return true;
}
bool ok2(vector<pair<int , int>> edges , int x , int y) {
for(int i = 0; i < edges.size(); ++ i) {
if((edges[i].F == x && edges[i].S == y) || (edges[i].F == y && edges[i].S == x)) {
return true;
}
}
return false;
}
void solve() {
int n , k , SAY = 0;
cin >> n >> k;
vector<int> vt(n);
int cem = 0;
for(int i = 0; i < n; ++ i) {
cin >> vt[i];
cem += vt[i];
}
vector<pair<int , int>> edges(n - 1);
for(int i = 0; i < n - 1; ++ i) {
int x , y;
cin >> x >> y;
edges[i].F = x;
edges[i].S = y;
}
vector<int> wreath;
wreath.pb(cem);
while(!ok1(wreath , k)) {
int mini = INT_MAX;
int a;
for(int i = 0; i < n; ++ i) {
int x = edges[i].F;
int y = edges[i].S;
int sum = 0 , sum1 = 0;
int say = 0 , say1 = 0;
vector<int> vt1 , vt2;
//////////////////////
int A = -1;
bool ok = false;
for(int j = 0; j < n; ++ j) {
if(i == j) {
continue;
}
if(ok2(edges , x , j + 1)) {
say++;
sum += vt[j];
if(A == -1) A = j + 1;
}
}
for(int j = 0; j < n; ++ j) {
if(i == j) {
continue;
}
if(ok2(edges , y , j + 1)) {
say1++;
sum1 += vt[j];
if(j + 1 == A) {
ok = true;
break;
}
}
}
//////////////////////
if(mini > abs(sum - sum1)) {
mini = abs(sum - sum1);
a = i;
}
}
edges.erase(edges.begin() + a);
SAY++;
wreath.clear();
vector<bool> vis(n + 1 , false);
for(int i = 1; i <= n; ++ i) {
if(vis[i] == true) {
continue;
}
vis[i] = true;
int sum = vt[i - 1];
int cem = vt[i - 1];
queue<int> q;
q.push(i);
while(!q.empty()) {
int u = q.front();
q.pop();
for(int i = 0; i < edges.size(); ++ i) {
int x = edges[i].F , y = edges[i].S;
int Z = -1;
if(x == u && vis[y] != false) Z = y;
if(y == u && vis[x] != false) Z = x;
if(x != -1) {
vis[Z] = true;
sum += vt[Z - 1];
q.push(Z);
}
}
wreath.pb(sum);
}
}
}
cout << SAY << endl;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
//sieve();
//pppp();
int t = 1;
//cin >> t;
//int n;
for(int i = 0; i < t; ++i) {
solve();
}
}
