#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int n;
  string instr;
  while (cin >> instr, !cin.eof()) {
    if (instr.length() % 2) {
      continue;
    }
    bool cannot = false;
    for (int i = 0; i < instr.length() - 1; i += 2) {
      if (instr[i] < '1' || instr[i] > '6' || instr[i + 1] < '1' ||
          instr[i + 1] > '5') {
        cannot = true;
        break;
      }
    }
    if (cannot) {
      cout << "NA" << endl;
      continue;
    }
    for (int i = 0; i < instr.length() - 1; i += 2) {
      int a = instr[i] - '0', b = instr[i + 1] - '0';
      int c = b + (a - 1) * 5;
      if (c <= 26)
        cout << (char)(c - 1 + 'a');
      else {
        switch (c % 26) {
          case 1:
            cout << '.';
            break;
          case 2:
            cout << '?';
            break;
          case 3:
            cout << '!';
            break;
          default:
            cout << ' ';
            break;
        }
      }
    }
    cout << endl;
  }
  return 0;
}
