#include<iostream>

using namespace std;
string str,ans;
char t[6][7]={
  {' ',' ',' ',' ',' ',' ',' '},
  {' ','a','f','k','p','u','z'},
  {' ','b','g','l','q','v','.'},
  {' ','c','h','m','r','w','?'},
  {' ','d','i','n','s','x','!'},
  {' ','e','j','o','t','y',' '}
};
bool check(char a,char b){
  if('1'<=a&&a<='6'){}else return false;
  if('1'<=b&&b<='5'){}else return false;
  return true;
}

int main(){
  while(cin>>str){
    ans="";
    for(int i=0;i<(int)str.size();i+=2){
      if(check(str[i],str[i+1])){
	ans.push_back(t[str[i+1]-'0'][str[i]-'0']);
      }else{
	ans="NA";
	break;
      }
    }
    cout<<ans<<endl;
  }
  return 0;
}