#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  string s;
  cin >> s;
  int n = s.length();
  int x = s.length() / 2;
  int p = 0;
  int n1 = n + 1;
  int q = 0;
  for (int i = 0; i < n1; i++) {
    for (int j = 97; j <= 122; j++) {
      string r = "";
      r.push_back(char(j));
      string r1 = s;
      r1.insert(i, r);
      int n2 = r1.length();
      int u = (n2) / 2;
      int l = 0;
      for (int h = 0; h < u; h++) {
        if (r1[h] != r1[n2 - 1 - h]) {
          l++;
        }
      }
      if (l == 0) {
        cout << r1;
        return 0;
      }
    }
  }
  cout << "NA";
  return 0;
}
