#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  long long MAX_CAP = 0;
  long long MAXI[100000 + 7];
  for (int i = int(0); i <= int(s.size() - 1); i++) {
    MAXI[i] = max((s[i] - 'a'), 25 - (s[i] - 'a'));
    MAX_CAP = MAX_CAP + MAXI[i];
  }
  if (k > MAX_CAP) {
    cout << "-1" << endl;
    return 0;
  }
  for (int i = int(0); i <= int(s.size() - 1); i++) {
    if (k == 0) break;
    if (k >= MAXI[i]) {
      if (s[i] + MAXI[i] > 'z') {
        s[i] = char(s[i] - MAXI[i]);
      } else if (s[i] - MAXI[i] < 'a') {
        s[i] = char(s[i] + MAXI[i]);
      }
      k = k - MAXI[i];
    } else if (k < MAXI[i]) {
      if (s[i] + k > 'z') {
        s[i] = char(s[i] - k);
      } else if (s[i] - k < 'a') {
        s[i] = char(s[i] + k);
      } else {
        s[i] = char(s[i] + k);
      }
      k = 0;
    }
  }
  cout << s << endl;
  return 0;
}
