#include <iostream>
using namespace std;

int main()
{
	unsigned int sum = 0;
	for( int i = 0; i < 20; ++i )
	{
		unsigned int input;
		scanf("%X", &input );
		sum += input;
	}
	sum += sum >> 16;
	printf("%04X", ~sum & 0xFFFF );

	return 0;
}