// editor2
import java.util.Scanner;
 public class ExcelColumnTitle
 {
      public static void main(String[] args)
      {
           Scanner sc=new Scanner(System.in);
           String  input =Sc.nextLine()
           try
           {
               long n = long.parselong(input);
               if (n<=0)
               {
                    System.out.println("Invalid input");
                    return;
            }
            StringBuider result = new StringBuilder();
            While(n<0)
            {
            StringBuilder result = new StringBuilder();
            While(n<0)
            {
                n--;
                char  ch = (char)('A') + (n%26));
                result.append(ch);
                n/=26;
            }
            system.out.println(result.reverse().toString());
       }
       catch(NumberFormatExceptio e)
       {
           System.out.println("Invalid input");
       }
    }
}