#include <bits/stdc++.h>
using namespace std;
int main() {
  string str;
  while (getline(cin, str)) {
    stringstream sin;
    bool flag = true;
    if ((int)str.length() % 2 == 0) {
      for (int i = 0; i < str.length(); i += 2) {
        int tm1 = (int)str[i] - (int)'0';
        int tm2 = (int)str[i + 1] - (int)'0';
        if (tm1 > 6 || tm2 > 5) {
          flag = false;
          break;
        }
        char c;
        if (tm1 == 6 && tm2 >= 2) {
          switch (tm2) {
            case 2:
              c = '.';
              break;
            case 3:
              c = '?';
              break;
            case 4:
              c = '!';
              break;
            case 5:
              c = ' ';
              break;
          }
        } else {
          c = (char)((tm1 - 1) * 5 + tm2 - 1 + (int)'a');
        }
        sin << c;
      }
    } else {
      flag = false;
    }
    if (!flag) {
      cout << "NA" << endl;
    } else {
      cout << sin.str() << endl;
    }
  }
  return 0;
}
