#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(long x) { cerr << x; }
void __print(long long x) { cerr << x; }
void __print(unsigned x) { cerr << x; }
void __print(unsigned long x) { cerr << x; }
void __print(unsigned long long x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template <typename T, typename V>
void __print(const pair<T, V> &x) {
  cerr << '{';
  __print(x.first);
  cerr << ',';
  __print(x.second);
  cerr << '}';
}
template <typename T>
void __print(const T &x) {
  int f = 0;
  cerr << '{';
  for (auto &i : x) cerr << (f++ ? "," : ""), __print(i);
  cerr << "}";
}
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v)) cerr << ", ";
  _print(v...);
}
template <typename T>
bool mmax(T &m, const T q) {
  if (m < q) {
    m = q;
    return true;
  } else
    return false;
}
template <typename T>
bool mmin(T &m, const T q) {
  if (m > q) {
    m = q;
    return true;
  } else
    return false;
}
const char en = '\n';
const int MOD = 0;
const int MAXN = 0;
const int INF = 1e9 + 1;
int solve() {
  int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  string t(n, ' ');
  for (int i = 0; i < (int)(n); ++i) {
    if (k == 0)
      t[i] = s[i];
    else {
      int c1 = s[i] - 'a';
      int c2 = 'z' - s[i];
      if (c1 > c2) {
        int d = min(k, c1);
        t[i] = (char)(s[i] - d);
        k -= d;
      } else {
        int d = min(k, c2);
        t[i] = (char)(s[i] + d);
        k -= d;
      }
    }
  }
  if (k)
    cout << -1;
  else
    cout << t;
  cout << en;
  return 0;
}
int main(int argc, char **argv) {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int ntest = 1;
  for (int test = 0; test < (int)(ntest); ++test) {
    solve();
  }
  return 0;
}
