#include <iostream>
#include <cstdint>

using namespace std;

static inline constexpr string solve(const string& S) noexcept
{
	if (S[0] == S[1] && S[1] != S[2]) return "Yes"s;
	else return "No"s;
}

int main()
{
	cin.tie(nullptr);
	ios::sync_with_stdio(false);

	string S;
	S.reserve(3);
	cin >> S;

	cout << solve(S) << '\n';
	return 0;
}