# imosっぽいな!!!
# 頼む！とおれ！

N,H = map(int,input().split())
L,R = [],[]
for i in range(N):
    a,b = map(int,input().split())
    L.append(a)
    R.append(b)

table = [0]*(H+1)
for i in range(N):
    table[L[i]] += 1 # 開始時刻
    table[R[i]+1] -= 1 # 終了時刻

for i in range(1,H+1):
    table[i] += table[i-1]

ans = 0
for i in range(H+1):
    ans = max(ans, table[i])
print(ans)