#include <bits/stdc++.h>
#include "atcoder/modint"

using i64 = long long;
using Fp = atcoder::modint998244353;

int main() {
    std::string S;
    std::cin >> S;
    if (S[0] == S[1] and S[0] != S[2]) std::cout << "Yes" << std::endl;
    else std::cout << "No" << std::endl;
}