#include<bits/stdc++.h>
using namespace std;
int main(){
  string str[6]={"","aafkpuz","abglqv.","achmrw?"
		 ,"adinsx!","aejoty "};
  string str2;
  while(cin>>str2){
    if(str2.size()%2==1)
      cout<<"NA"<<endl;
    else{
      for(int i=0;i<str2.size();i+=2){
	cout<<str[str2[i+1]-'0'][str2[i]-'0'];
      }
      cout<<endl;
    }
  }
  return 0;
}