#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;
    }
    string ans="";
    for(int i=0;i<s.size();i+=2){
      int y=s[i+1]-'1';
      int x=s[i]-'1';
      if(y<0 || y>4 || x<0 || x>5){
	ans="NA";
	break;
      }
      else ans+=data[y][x];
    }
    cout<< ans;     
    cout<< endl;
  }
}