n, h = map(int, input().split())
t = [0] * 10**6
for _ in range(n):
    l, r = map(int, input().split())
    t[l] += 1
    t[r + 1] -= 1
ans, now = 0, 0
for i in range(h + 5):
    now += t[i]
    ans = max(ans, now)
print(ans)