C :

#include<stdio.h>
int main()
{
	int a;
	scanf("%X",&a);
	printf("%d\n",a);
	return 0;
}

C++ :

#include <stdio.h>
#include <string.h>
int main() {
	int trans(char str[]);
	char str[20];
	gets(str);
	printf("%d\n", trans(str));
	return 0;
}
int trans(char str[]) {
	int i, val = 0;
	for (i = 0;str[i] != '\0';i++) {
		if ('0' <= str[i] && str[i] <= '9')
			val = val * 16 + (str[i] - '0');
		else
			val = val * 16 + (str[i] - 'a' + 10);
	}
	return val;
}

Pascal :

var
  s:string;
  i,code:longint;
begin
  readln(s);
  s:='$'+s;
  val(s,i,code);
  writeln(i);
end.

Java :

//import java.util.LinkedList;
//import java.util.List;
import java.util.Scanner;

public class Main {
   private static Scanner s = new Scanner(System.in) ;
   public static void main(String[] args) {
	   String str = s.next() ;
	   System.out.println(Integer.parseInt(str,16)); 
   }
}