#include <stdio.h>

int main()
{
	int a, b, c;
	scanf("%d %d %d", &a, &b, &c);
	if (a == b && b == c) printf("%d\n", a);
	else if (a == b || b == c || c == a) printf("%d\n", a ^ b ^ c);
	else printf("%d\n", 6 - a - b - c);
	fflush(stdout);
	return 0;
}