n, hour = map(int, input().split())
data = [list(map(int, input().split())) for _ in range(n)]
ans = 0

for i in range(hour):
	count = 0
	for j in range(n):
		if data[j][0] <= i <= data[j][1]:
			count += 1
	ans = max(ans,count)
	
print(ans)