import sys

input = sys.stdin.buffer.readline

N, H = map(int, input().split())
imos = [0] * (H + 1)
for _ in range(N):
    A, B = map(int, input().split())
    imos[A] += 1
    imos[B + 1] -= 1

for i in range(H):
    imos[i + 1] += imos[i]
print(max(imos))