import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
class Main {
public static final String HEX_DIGITS = "0123456789ABCDEF";
public static String hexToDec(String hex) {
char[] sources = hex.toCharArray();
int dec = 0;
for (int i = 0; i < sources.length; i++) {
int digit = HEX_DIGITS.indexOf(Character.toUpperCase(sources[i]));
dec += digit * Math.pow(16, (sources.length - (i + 1)));
}
return String.valueOf(dec);
}
}