#include <bits/stdc++.h>   using namespace std;   vector<int> v[200008];   int val[200008];   int n, tk;   int dp[200008];   int lim;   int siz[200008];   int cnt, tot;   int no[200008];   void dfs(int x, int p) {     no[x] = val[x] < lim;     dp[x] = 0;     int b1 = 0, b2 = 0, b3 = 0;     siz[x] = 1;     for (int i = 0; i < v[x].size(); i++) {       int y = v[x][i];       if (y == p) continue;       dfs(y, x);       siz[x] += siz[y], no[x] += no[y];       if (no[y] == 0)         b3 += siz[y];       else {         if (dp[y] > b1)           b2 = b1, b1 = dp[y];         else           b2 = max(b2, dp[y]);       }     }     if (val[x] < lim) return;     dp[x] = b1 + b3 + 1;     if (tot == no[x])       cnt = max(cnt, 1 + n - siz[x] + b1 + b2 + b3);     else       cnt = max(cnt, 1 + b1 + b2 + b3);   }   int check(int mid) {     lim = mid;     cnt = 0;     tot = 0;     for (int i = 1; i <= n; i++)       if (val[i] < lim) tot++;     dfs(1, 0);     return cnt >= tk;   }   int main() {     scanf( %d%d , &n, &tk);     for (int i = 1; i <= n; i++) scanf( %d , &val[i]);     for (int i = 1; i < n; i++) {       int x, y;       scanf( %d%d , &x, &y);       v[x].push_back(y);       v[y].push_back(x);     }     int l = 0, r = 1000000;     int ans = -1;     while (l <= r) {       int mid = (l + r) / 2;       if (check(mid))         ans = mid, l = mid + 1;       else         r = mid - 1;     }     cout << ans;     return 0;   }   