Kaspichan_1

import java.util.Scanner;

public class Temp_1 {
    public static void main(String[] args) {
        // array of 256 elements
        long baseNum = 256;
        String[] arr = GenerateNumberArray(256);

        // read input
        Scanner in = new Scanner(System.in);
        //long input = in.nextLong();
        String type = in.next("\\d{1,21}");
        Long input = Long.parseUnsignedLong(type);

        // calculations
        String result = "";
        if (input == 0) {
            result = "A";
        }
        else {
            while (input > 0) {
                long index = input % baseNum;
                result = arr[Math.toIntExact(index)] + result;
                input /= baseNum;
            }
        }
        // output
        System.out.println(result);


    }
	//Method for coding letter elements
    private static String[] GenerateNumberArray(int numBase) {
        String[] arr = new String[numBase];
        for (int i = 0; i < numBase; i++) {
            if (i < 26) { //solve for first 26
                arr[i] = String.format("%s", (char) (i + 'A'));
                // System.out.printf("%s%n", arr[i]); //Check of coding up to 26
            }
            else {
                arr[i] = String.format("%s%s",
                        (char)(i/26-1+'a'),
                        (char)(i%26+'A'));
            }
            //System.out.printf("%s%n",arr[i]); //Check of coding after 26
        }
        return arr;
    }

}