import java.util.Scanner;

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

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

        int n = sc.nextInt();

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

        // Convert number to Excel column title
        StringBuilder columnTitle = new StringBuilder();
        while (n > 0) {
            n--; // Adjust to 0-based index
            int remainder = n % 26;
            columnTitle.append((char) ('A' + remainder));
            n /= 26;
        }

        // Reverse result since we built it backwards
        System.out.println(columnTitle.reverse().toString());
    }
}