#include <bits/stdc++.h>
using namespace std;
int main(int qtd, char* nome[]) {
  int n, k;
  scanf("%d %d", &n, &k);
  char s[(int)3e5 + 2];
  scanf("%s", s);
  long long mxK = 0;
  vector<int> v(n);
  for (int i = 0; i < n; i++) {
    v[i] = max(s[i] - 'a', 'z' - s[i]);
    mxK += v[i];
  }
  if (mxK < k)
    printf("-1\n");
  else {
    char ans[n + 1];
    for (int i = 0; i < n; i++) {
      if (k - v[i] >= 0) {
        ans[i] = (s[i] + v[i] <= 'z' ? s[i] + v[i] : s[i] - v[i]);
        k -= v[i];
      } else {
        ans[i] = (s[i] + k <= 'z' ? s[i] + k : s[i] - k);
        k = 0;
      }
    }
    ans[n] = '\0';
    printf("%s\n", ans);
  }
  return 0;
}
