#![allow(unused_imports)]
#![allow(non_snake_case)]
use std::cmp::*;
use std::collections::*;
use std::io::Write;

#[allow(unused_macros)]
macro_rules! debug {
    ($($e:expr),*) => {
        #[cfg(debug_assertions)]
        $({
            let (e, mut err) = (stringify!($e), std::io::stderr());
            writeln!(err, "{} = {:?}", e, $e).unwrap()
        })*
    };
}

fn main() {
    let n = read::<usize>();
    let a = read_vec::<i64>();

    let mut dp = vec![0i64; n + 1];
    dp[0] = 1;

    for i in 1..n {
        if a[i] == a[i - 1] {
            dp[i] = max(dp[i], dp[i - 1] + 1);
        }
        if i >= 2 {
            dp[i] = max(dp[i], dp[i - 2] + 1);
        }
        if i >= 3 {
            dp[i] = max(dp[i], dp[i - 3] + 1);
        }
    }
    println!("{}", dp.iter().max().unwrap());
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}