#include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     for (int i = 0; i < s.size(); i++) {       for (char a =  a ; a <=  z ; a++) {         string t =   ;         for (int j = 0; j < i; j++) {           t += s[j];         }         t += a;         for (int j = i; j < s.size(); j++) {           t += s[j];         }         string r = t;         reverse(t.begin(), t.end());         if (r == t) {           cout << r;           return 0;         }       }     }     for (char a =  a ; a <=  z ; a++) {       string t = s;       t += a;       string r = t;       reverse(t.begin(), t.end());       if (r == t) {         cout << r;         return 0;       }     }     cout <<  NA ;   }   