package main

import . "fmt"
import . "os"
import bf "bufio"

func main() {
	rd := bf.NewReader(Stdin)
	var n,h int
	Fscan(rd, &n, &h)
	tt := make([]int, h+1)
	for i := 0; i < n; i++ {
		var a, b int
		Fscan(rd, &a, &b)
		tt[a]++
		tt[b+1]--
	}
	ans := 0
	cnt := 0
	for _, c := range tt {
		cnt += c
		if cnt > ans {
			ans = cnt
		}
	}
	Println(ans)
}