import sys
input = sys.stdin.readline

N,H=map(int,input().split())

S=[0]*(1010100)

for i in range(N):
    a,b=map(int,input().split())
    S[a]+=1
    S[b+1]-=1

for i in range(1010100):
    S[i]+=S[i-1]

print(max(S))