use proconio::input;

fn main() {
    input! {
        n: usize,
        h: usize,
        ab: [(usize, usize); n],
    }
    let mut diff = vec![0; h + 1];
    for &(a, b) in &ab {
        diff[a] += 1;
        diff[b + 1] -= 1;
    }
    let mut ans = 0;
    let mut cnt = 0;
    for &diff in &diff {
        cnt += diff;
        ans = ans.max(cnt);
    }
    println!("{}", ans);
}