package main
import (
    "fmt"
    "bufio"
    "strconv"
    "strings"
    "os"
)

func main() {
    var n int
    var tree *node
    scanner := bufio.NewScanner(os.Stdin)
    for scanner.Scan() {
        text := scanner.Text()
        if n == 0 {
            n, _ = strconv.Atoi(text)
            continue
        }
        for _, s := range strings.Fields(text) {
            if v, err := strconv.Atoi(s); err == nil {
                tree = insert(tree, &node{value:v})
            }
        }
    }
    fmt.Println(height(tree, 0))
}

type node struct{
    value int
    left *node
    right *node
}

func insert(root, n *node) *node {
    if root == nil {
        return n
    }
    if n.value < root.value {
        root.left = insert(root.left, n)
        return root
    }
    root.right = insert(root.right, n)
    return root
}

func height(root *node, currentHeight int) int {
    if root == nil {
        return -1
    }

    maxHeight := currentHeight

    if root.left != nil {
       if nh := height(root.left, currentHeight+1); nh > maxHeight {
           maxHeight = nh
       } 
    }

    if root.right != nil {
       if nh := height(root.right, currentHeight+1); nh > maxHeight {
           maxHeight = nh
       } 
    }

    return maxHeight
}