use proconio::input;

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

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

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