#include <stdio.h>

int main(void)
{
	char mask[16];

	mask['0']='0000';
	mask['1']='0001';
	mask['2']='0010';
	mask['3']='0011';
	mask['4']='0100';
	mask['5']='0101';
	mask['6']='0110';
	mask['7']='0111';
	mask['8']='1000';
	mask['9']='1001';
	mask['a']='1010';
	mask['b']='1011';
	mask['c']='1100';
	mask['d']='1101';
	mask['e']='1110';
	mask['f']='1111';

	puts(mask[0]);

	return 0;
}