#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr char solve(const char a, const char b, const char c) noexcept
{
	if (a == b) return c;
	else if (a == c) return b;
	else if (b == c) return a;
	else return (('0' + '1' + '2' + '3') - (a + b + c));
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	
	char a, b, c;
	std::cin >> a >> b >> c;

	std::cout << solve(a, b, c) << '\n';
	return 0;
}