import java.util.*;
public class main
{
    public static void main(String[] args)
    {
        Scanner sc=new Scanner(System.in);
        if (!sc.hasNextInt())
        {
            System.out.println("Invalid input");
            return;
        }
        
        if (n<=0)
        {
            int a=sc.nextInt();
            System.out.println("Invalid input");
            return;
        }
        StringBuilder columnTitle=new StringBuilder();
        while (n>0)
        {
            n--;
            int remainder=n%26;
            columnTitle.insert(0,(char)('A'+remainder));
            n=n/26;
        }
        System.out.println(columnTitle.toString());
    }
}