#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1000000000 + 7;
const long long int N = 10000000 + 6;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n, k;
  cin >> n >> k;
  string st;
  cin >> st;
  long long int ma = 0;
  for (char k : st) {
    ma = ma + max(k - 'a', 'z' - k);
  }
  if (ma < k)
    cout << -1 << '\n';
  else {
    string str;
    for (char i : st) {
      int f = min(k, i - 'a');
      int g = min(k, 'z' - i);
      if (f > g) {
        k -= f;
        str.push_back(i - f);
      } else {
        k -= g;
        str.push_back(i + g);
      }
    }
    cout << str;
  }
  return 0;
}
