#include <bits/stdc++.h>
using namespace std;
char META_CHARACTER[] = "z.?! ";
int main(void) {
  for (string in, out; cin >> in; cout << out << endl) {
    out.clear();
    if (in.length() % 2) {
      out = "NA";
      continue;
    }
    for (int i = 0; i < in.length(); i += 2) {
      int col = in.at(i) - '1';
      int row = in.at(i + 1) - '1';
      if (col == 5) {
        out.push_back(META_CHARACTER[row]);
      } else {
        out.push_back('a' + 5 * col + row);
      }
    }
  }
  return 0;
}
