#include<bits/stdc++.h>
using namespace std;

int main(){
  string s;
  char data[5][7]={
    "afkpuz",
    "bglqv.",
    "chmrw?",
    "dinsx!",
    "ejoty "
  };

  while(cin>> s){
    if(s.size()%2){
      cout<< "NA"<< endl;
      continue;
    }

    for(int i=0;i<s.size();i+=2){
      cout<< data[s[i+1]-'1'][s[i]-'1'];      
    }
    cout<< endl;
  }
}