#include <bits/stdc++.h>
using namespace std;
string str, ch;
int isPalindrome(int l, string c) {
  int i;
  for (i = 0; i < l / 2; i++)
    if (c[i] != c[l - i - 1]) return 0;
  return 1;
}
void String_Concatanate(char a, int pos, int l) {
  int i;
  for (i = 0; i < pos; i++) ch.push_back(str[i]);
  ch.push_back(a);
  for (i = pos; i < l; i++) ch.push_back(str[i]);
}
int main() {
  cin >> str;
  int i, j, l;
  l = str.size();
  if (isPalindrome(l, str)) {
    for (i = 0; i < l / 2; i++) cout << str[i];
    cout << str[i];
    for (i = l / 2; i < l; i++) cout << str[i];
    return 0;
  } else {
    for (i = 97; i <= 122; i++)
      for (j = 0; j <= l; j += 1) {
        String_Concatanate(i, j, l);
        if (isPalindrome(l + 1, ch)) {
          cout << ch << endl;
          return 0;
        }
        ch.erase();
      }
  }
  cout << "NA" << endl;
  return 0;
}
