#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int t = 1;
  while (t--) {
    int n, k;
    cin >> n >> k;
    char s[n + 1];
    cin >> s;
    int a = 0;
    for (int i = 0; i < n; i++) a += (max(int(s[i] - 'a'), int('z' - s[i])));
    if (k > a) return cout << -1, 0;
    for (int i = 0; i < n; i++) {
      if (s[i] - 'a' >= 'z' - s[i]) {
        int u = min(int(s[i] - 'a'), k);
        cout << char(s[i] - u);
        k -= u;
      } else {
        int u = min(int('z' - s[i]), k);
        cout << char(s[i] + u);
        k -= u;
      }
    }
  }
  return 0;
}
