#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 17;
int n, k, jhghajkhja, oauighgajk;
char a[N], b[N];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int i;
  scanf("%d %d", &n, &k);
  scanf("%s", a + 1);
  for (i = 1; i <= n; i++) b[i] = a[i];
  for (i = 1; i <= n && k > 0; i++) {
    jhghajkhja = a[i] - 'a';
    oauighgajk = 'z' - a[i];
    if (jhghajkhja > oauighgajk) {
      jhghajkhja = min(jhghajkhja, k);
      k -= jhghajkhja;
      b[i] -= jhghajkhja;
    } else {
      oauighgajk = min(oauighgajk, k);
      k -= oauighgajk;
      b[i] += oauighgajk;
    }
  }
  if (k == 0) {
    for (i = 1; i <= n; i++) printf("%c", b[i]);
    printf("\n");
  } else {
    printf("-1\n");
  }
  return 0;
}
