#include <bits/stdc++.h>
using namespace std;
vector<string> vec_splitter(string s) {
  s += ',';
  vector<string> res;
  while (!s.empty()) {
    res.push_back(s.substr(0, s.find(',')));
    s = s.substr(s.find(',') + 1);
  }
  return res;
}
void debug_out(vector<string> __attribute__((unused)) args,
               __attribute__((unused)) int idx,
               __attribute__((unused)) int LINE_NUM) {
  cerr << endl;
}
template <typename Head, typename... Tail>
void debug_out(vector<string> args, int idx, int LINE_NUM, Head H, Tail... T) {
  if (idx > 0)
    cerr << ", ";
  else
    cerr << "Line(" << LINE_NUM << ") ";
  stringstream ss;
  ss << H;
  cerr << args[idx] << " = " << ss.str();
  debug_out(args, idx + 1, LINE_NUM, T...);
}
long long int maxpem(string s) {
  long long int sum = 0;
  for (long long int(i) = 0; (i) < (s.size()); (i)++) {
    long long int loc = (s[i] - 'a');
    long long int gap = max(loc, 25 - loc);
    sum += gap;
  }
  return sum;
}
void solve() {
  long long int n, k;
  cin >> n >> k;
  string s;
  cin >> s;
  if (k > maxpem(s)) {
    cout << -1;
    return;
  }
  for (long long int(i) = 0; (i) < (n); (i)++) {
    long long int loc = s[i] - 'a';
    long long int gap = max(loc, 25 - loc);
    if (gap >= k) {
      if (loc + k > 25)
        s[i] -= k;
      else
        s[i] += k;
      break;
    } else {
      if (loc + gap > 25)
        s[i] -= gap;
      else
        s[i] += gap;
      k -= gap;
    }
  }
  cout << s << "\n";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  solve();
  return 0;
}
