import math
import heapq
import itertools
import bisect
import random
import time
from collections import deque
import sys
from cmath import exp,pi
from functools import cmp_to_key
input=sys.stdin.readline

n,h=map(int,input().split())
s=[0]*(h+5)
for i in range(n):
    a,b=map(int,input().split())
    s[a]+=1
    s[b+1]-=1

for i in range(1,len(s)):
    s[i]+=s[i-1]
print(max(s))