#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  long long mxs = 0;
  for (char x : s) mxs += max(x - 'a', 'z' - x);
  if (mxs < k)
    cout << -1 << endl;
  else {
    string ans = s;
    for (long long i = 0; i < n; i++) {
      if (s[i] - 'a' > 'z' - s[i]) {
        ans[i] = s[i] - min(k, (long long)(s[i] - 'a'));
        k -= min(k, (long long)(s[i] - 'a'));
      } else {
        ans[i] = s[i] + min(k, (long long)('z' - s[i]));
        k -= min(k, (long long)('z' - s[i]));
      }
    }
    cout << ans << endl;
  }
  return 0;
}
