N, H = map(int, input().split())
D = [0] * (H + 1)
for _ in range(N):
    a, b = map(int, input().split())
    D[a] += 1
    D[b+1] -= 1
S = [D[0]]
M = S[0]
for i in range(1, H + 1):
    S.append(S[-1] + D[i])
    if S[-1] > M:
        M = S[-1]
print(M)
# print(S)