#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  char data[5][7] = {"afkpuz", "bglqv.", "chmrw?", "dinsx!", "ejoty "};
  while (cin >> s) {
    if (s.size() % 2) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < s.size(); i += 2) {
      cout << data[s[i + 1] - '1'][s[i] - '1'];
    }
    cout << endl;
  }
}
