n, h = map(int, input().split())
H = [0] * (h+1)
for _ in range(n):
    a, b = map(int, input().split())
    H[a] += 1
    H[b+1] -= 1
ans = 0
for now in range(h+1):
    if now:
        H[now] += H[now-1]
    ans = max(ans, H[now])
print(ans)