import java.util.Scanner;

public class BinToHex {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String binInput = scanner.nextLine();
        switch (binInput.length() % 4) {
            case 0: break;
            case 1: binInput = "000" + binInput; break;
            case 2: binInput = "00" + binInput; break;
            case 3: binInput = "0" + binInput; break;
        }

        StringBuilder hexOut = new StringBuilder();



        for (int i = 0; i < binInput.length(); i+=4) {
            StringBuilder tempBuild = new StringBuilder();
            tempBuild = tempBuild.append(binInput.charAt(i));
            tempBuild = tempBuild.append(binInput.charAt(i+1));
            tempBuild = tempBuild.append(binInput.charAt(i+2));
            tempBuild = tempBuild.append(binInput.charAt(i+3));

            switch (tempBuild.toString()) {
                case "0000": hexOut.append("0"); break;
                case "0001": hexOut.append("1"); break;
                case "0010": hexOut.append("2"); break;
                case "0011": hexOut.append("3"); break;
                case "0100": hexOut.append("4"); break;
                case "0101": hexOut.append("5"); break;
                case "0110": hexOut.append("6"); break;
                case "0111": hexOut.append("7"); break;
                case "1000": hexOut.append("8"); break;
                case "1001": hexOut.append("9");; break;
                case "1010": hexOut.append("A"); break;
                case "1011": hexOut.append("B"); break;
                case "1100": hexOut.append("C"); break;
                case "1101": hexOut.append("D"); break;
                case "1110": hexOut.append("E"); break;
                case "1111": hexOut.append("F"); break;
            }
        }
        System.out.println(hexOut);

    }
}