import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;

public class hh {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        BigInteger x =  sc.nextBigInteger();


        ArrayList<String> alpha = new ArrayList<>();

        for (char i ='A';i<='Z';i++){

            alpha.add(Character.toString(i));
        }
        for (char i= 'a';i<='i';i++){
            for(char j = 'A';j<='Z';j++){
                alpha.add(Character.toString(i)+j);
            }
        }
        String result = "";
        if(x.compareTo(BigInteger.valueOf(0))==0){
            result = "A";
        }
        while(x.compareTo(BigInteger.valueOf(0))>0){
            Integer index = (x.remainder(BigInteger.valueOf(256))).intValue();
            result = alpha.get(index) + result;
            x = (x.divide(BigInteger.valueOf(256)));
        }
        System.out.println(result);

    }
}