#include <bits/stdc++.h>
using namespace std;
int n, k;
char s[1123456];
int dist() {
  int ret = 0;
  for (int i = 0; i < n; i++) {
    int myval = s[i] - 'a';
    myval = max(myval, 25 - myval);
    ret += myval;
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  scanf("%d %d %s", &n, &k, s);
  if (k > dist())
    printf("-1\n");
  else {
    int x = 0;
    for (int i = 0; i < n; i++) {
      if (x < k) {
        int myval = s[i] - 'a';
        if (myval > 25 - myval) {
          int dif = min(k - x, myval);
          x += dif;
          s[i] -= dif;
        } else {
          int dif = min(k - x, 25 - myval);
          x += dif;
          s[i] += dif;
        }
      }
      printf("%c", s[i]);
    }
    printf("\n");
  }
}
