#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     int n, k;     cin >> n >> k;     string s;     cin >> s;     string res =   ;     for (int i = 0; i < n; i++) {       if ((s[i] -  a ) >= ( z  - s[i])) {         if ((s[i] -  a ) <= k) {           k -= (s[i] -  a );           res +=  a ;         } else {           res += (char)(s[i] - k);           k = 0;         }       } else {         if (( z  - s[i]) <= k) {           k -= ( z  - s[i]);           res +=  z ;         } else {           res += (char)(s[i] + k);           k = 0;         }       }     }     if (k != 0) {       cout << -1;     } else {       cout << res;     }   }   