#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int k;
  cin >> k;
  string s, t;
  cin >> s;
  t = s;
  for (int i = 0; i < s.length() && k; i++) {
    if (s[i] - k >= 'a') {
      t[i] = s[i] - k;
      k = 0;
    } else if (s[i] + k <= 'z') {
      t[i] = s[i] + k;
      k = 0;
    } else if (s[i] - 'a' > 'z' - s[i]) {
      if (s[i] - 'a' <= k) {
        t[i] = 'a';
        k -= (s[i] - 'a');
      } else {
        if ('z' - s[i] <= k) {
          t[i] = 'z';
          k -= ('z' - s[i]);
        }
      }
    } else {
      if ('z' - s[i] <= k) {
        t[i] = 'z';
        k -= ('z' - s[i]);
      } else {
        cout << "!";
        if (s[i] - 'a' <= k) {
          t[i] = 'a';
          k -= (s[i] - 'a');
        }
      }
    }
  }
  if (k != 0)
    cout << "-1";
  else
    cout << t << endl;
  return 0;
}
