#include <bits/stdc++.h>
using namespace std;
int main() {
  string data[6] = {"", " afkpuz", " bglqv.", " chmrw?", " dinsx!", " ejoty "};
  string s;
  while (cin >> s) {
    string ans = "";
    if (s.size() % 2 != 0) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < s.size(); i += 2) {
      int x = s[i] - '0', y = s[i + 1] - '0';
      if (1 <= x && x <= 6 && 1 <= y && y <= 5) {
        ans += data[y][x];
      } else {
        cout << "NA" << endl;
        continue;
      }
    }
    cout << ans << endl;
  }
}
