#include <bits/stdc++.h>
using namespace std;
char s[100010];
int main() {
  memset(s, '\0', sizeof(s));
  int n, k;
  scanf("%d%d", &n, &k);
  scanf("%s", s);
  int ans = 0;
  for (int i = 0; i < n; i++) {
    int a = s[i] - 'a';
    int b = 'z' - s[i];
    ans += ((a) > (b) ? (a) : (b));
  }
  if (ans < k)
    printf("-1\n");
  else {
    for (int i = 0; i < n; i++) {
      int a = ((s[i] - 'a') > ('z' - s[i]) ? (s[i] - 'a') : ('z' - s[i]));
      int x = (s[i] - 'a') > ('z' - s[i]) ? -1 : 1;
      if (a >= k) {
        s[i] = s[i] + x * k;
        printf("%s\n", s);
        break;
      } else {
        k -= a;
        s[i] = s[i] + x * a;
      }
    }
  }
  return 0;
}
