#include <bits/stdc++.h>
using namespace std;
string s;
int n, k;
inline int dis(char a, char b) {
  int x = a - 'a';
  int y = b - 'a';
  return abs(x - y);
}
inline void move(int i, int d) {
  if (dis(s[i], 'a') >= d) {
    int tmp = int(s[i] - 'a') - d;
    s[i] = char(tmp + 'a');
    return;
  }
  int tmp = int(s[i] - 'a') + d;
  s[i] = char(tmp + 'a');
  return;
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cin >> n >> k >> s;
  for (int i = 0; i < n; i++) {
    int mx = max(dis(s[i], 'a'), dis(s[i], 'z'));
    move(i, min(k, mx));
    k -= min(k, mx);
  }
  if (k) return cout << -1, 0;
  return cout << s, 0;
}
