use proconio::input;

fn main() {
    input! {
        (n, h): (usize, usize),
        ab: [(usize, usize); n],
    }

    let mut imos = vec![0_i64; h + 1];
    for &(a, b) in &ab {
        imos[a] += 1;
        imos[b + 1] -= 1;
    }
    for i in 0..h {
        imos[i + 1] += imos[i];
    }

    println!("{}", imos.iter().max().unwrap());
}