use proconio::input;

fn main() {
    input! {
        n: usize,
        aa: [u8; n],
    }

    let is_ok = |seq: &[u8]| seq.windows(2).any(|window| window[0] == window[1]);

    let ans = (0..n - 1).any(|i| {
        let mut swapped = aa.clone();
        swapped.swap(i, i + 1);
        is_ok(&swapped)
    });
    println!("{}", if ans { "Yes" } else { "No" });
}