#include <iostream>
using namespace std;
string str[] = {"abkpuz",
		"bglqv.",
		"chmrw?",
		"dinsx!",
		"ejoty "};
int main(){
  string str2;
  cin >> str2; 
     string ans="";
    if(str2.size()%2 == 1){
      cout << "NA" << endl;
    }
    for(int i = 0 ; i < str2.size() ; i+=2){
      ans += str[str2[i+1] - '0'-1][str2[i] - '0'-1]; 
    }
    cout << ans << endl;
  return 0;
}