#include <bits/stdc++.h>
using namespace std;
string str[] = {"abkpuz", "bglqv.", "chmrw?", "dinsx!", "ejoty "};
int main() {
  string str2;
  cin >> str2;
  string ans = "";
  if (str2.size() % 2 == 1) {
    cout << "NA" << endl;
  }
  for (int i = 0; i < str2.size(); i += 2) {
    ans += str[str2[i + 1] - '0' - 1][str2[i] - '0' - 1];
  }
  cout << ans << endl;
  return 0;
}
