#include <bits/stdc++.h>
using namespace std;
int main() {
  string a;
  while (1) {
  k:;
    cin >> a;
    if (cin.fail()) break;
    if (a.length() % 2) {
      cout << "NA" << endl;
      continue;
    }
    for (int b = 0; b < a.length(); b += 2) {
      if (a[b] < '1' || a[b] > '6' || a[b + 1] < '1' || a[b + 1] > '5') {
        cout << "NA" << endl;
        goto k;
      }
      int s = (a[b] - 49) * 5 + (a[b + 1] - 49);
      if ((s + 97) < '{')
        cout << (char)(s + 97);
      else {
        switch (s + 97) {
          case 123:
            cout << '.';
            break;
          case 124:
            cout << '?';
            break;
          case 125:
            cout << '!';
            break;
          case 126:
            cout << ' ';
            break;
        }
      }
    }
    cout << endl;
  }
}
