#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-11;
const int INFINITE = 0x3f3f3f3f;
template <class T>
inline void swap(T &a, T &b) {
  T temp = a;
  a = b;
  b = temp;
}
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T gcd(T a, T b) {
  T c;
  while (a != 0) {
    c = a;
    a = b % a;
    b = c;
  }
  return b;
}
template <class T>
inline T inv(T a, T b) {
  return 1 < a ? b - inv(b % a, a) * b / a : 1;
}
typedef vector<int> VI;
typedef vector<VI> VII;
typedef vector<string> VS;
const int MAXN = (int)1e5 + 1;
char s[MAXN];
inline int dist(char a, char b) {
  if (!(a >= 'a' && a <= 'z') || !(b >= 'a' && b <= 'z')) return -1;
  int ret = abs(b - a);
  return ret;
}
inline void solve() {
  int n, k;
  scanf("%d%d\n", &n, &k);
  scanf("%s", s);
  int len = strlen(s), tk = k;
  if (len * 25 < k) {
    printf("-1\n");
    return;
  }
  string res(s);
  for (int i = (0); i < int(len); i++) {
    int p = (int)(s[i] - 'a');
    int cp = 25 - p;
    if (p > cp) {
      int d = min(p, k);
      res[i] = (char)(s[i] - d);
      k -= d;
    } else {
      int d = min(cp, k);
      res[i] = (char)(s[i] + d);
      k -= d;
    }
  }
  if (k > 0) {
    printf("-1\n");
    return;
  }
  int di = 0;
  for (int i = (0); i < int(len); i++) di += dist(res[i], s[i]);
  assert(di == tk);
  printf("%s\n", res.c_str());
}
int main() {
  ios::sync_with_stdio(false);
  solve();
  return 0;
}
