fn main() {
    let n = read::<usize>();
    let mut a = vec![];
    for i in 0..n {
        a.push(read::<i64>());
    }
    if (0..n - 1).all(|i| a[i + 1] - a[i] > 1) {
        println!("1");
    } else {
        println!("2");
    }
}

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()
}