#![allow(dead_code)]

fn input_num() -> usize {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    line.trim().parse().unwrap()
}

fn input_chars() -> Vec<char> {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    line.trim().chars().collect()
}

fn input_nums() -> (usize, f64, f64) {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    let mut iter = line.split_whitespace();
    (
        iter.next().unwrap().parse().unwrap(),
        iter.next().unwrap().parse().unwrap(),
        iter.next().unwrap().parse().unwrap()
    )
}

fn input_vec_nums() -> Vec<usize> {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    line.split_whitespace()
        .map(|x| x.parse().unwrap())
        .collect()
}

fn input_str() -> String {
    let mut line: String = String::new();
    std::io::stdin().read_line(&mut line).unwrap();
    for _ in 0..2 { line.remove(line.len() - 1); }
    line
}

fn main() {
    let s = input_chars();
    if s[0] == s[1] && s[0] != s[2] {
        println!("Yes");
    } else {
        println!("No");
    }
}