let nk = readLine()!.split(separator: " ").map{Int($0)!}
let (n,h) = (nk[0],nk[1])
var arr = [Int](repeating: 0, count: h+1)
for i in 1...n{
    let ab = readLine()!.split(separator: " ").map{Int($0)!}
    let (a,b) = (ab[0],ab[1])
    arr[a] += 1
    arr[b+1] -= 1
}
for i in 0..<h{
    arr[i+1] += arr[i]
}
var Max = 0
for i in 0..<h{
    Max = max(Max,arr[i])
}
print(Max)