#include <iostream>
using namespace std;

int main() {
  int i, p, q;
  bool b;
  char buf[201];
  char code[5][6] = {
    {'a', 'f', 'k', 'p', 'u', 'z'},
    {'b', 'g', 'l', 'l', 'q', 'v'},
    {'c', 'h', 'm', 'r', 'w', '?'},
    {'d', 'i', 'n', 's', 'x', '!'},
    {'e', 'j', 'o', 't', 'y', ' '},
  };

  while (cin.getline(buf, sizeof(buf))) {
    i = 0;
    b = true;
    while (buf[i]!='\0') {
      if (i&1) {
        if (buf[i]<'1'||buf[i]>'5') {
          b = false;
          break;
        }
      } else {
        if (buf[i]<'1'||buf[i]>'6') {
          b = false;
          break;
        }
      }
      ++i;
    }
    if (i&1) b = false;

    if (b) {
      i = 0;
      while (buf[i]!='\0') {
        p = buf[i++]-'1';
        q = buf[i++]-'1';
        cout << code[q][p];
      }
      cout << endl;
    } else {
      cout << "NA" << endl;
    }
  }
  return 0;
}