import java.util.Scanner;

public class ExcelColumnTitle 
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);

        
        if (!sc.hasNextInt()) {
            System.out.println("Invalid input");
            return;
        }

        int n = sc.nextInt();


        if (n <= 0) {
            System.out.println("Invalid input");
            return;
        }

        StringBuilder columnTitle = new StringBuilder();

        // Convert number to Excel column title
        while (n > 0) {
            n--; // Adjust for 1-based indexing
            int remainder = n % 26;
            columnTitle.insert(0, (char) ('A' + remainder));
            n = n / 26;
        }

        System.out.println(columnTitle.toString());
    }
}