import java.util.*;

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;
        }
        long n = sc.nextLong();

        // Check constraints
        if (n <= 0 || n > 2147483647L) {
            System.out.println("Invalid input");
            return;
        }

        // Convert number to Excel column title
        StringBuilder columnTitle = new StringBuilder();
        while (n > 0) {
            n--; // adjust because A=1 not 0
            char ch = (char) ('A' + (n % 26));
            columnTitle.insert(0, ch);
            n /= 26;
        }

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