import java.util.Scanner; class Main{ public static void main(String[] args) { Scanner in= new Scanner(System.in); while(in.hasNext()){ int n = in.nextInt(); int[] tree = new int[n]; for (int i = 0; i < tree.length; i++) { tree[i]=-1; } for(int i =0;i<n-1;i++){ int p = in.nextInt(); int c = in.nextInt(); tree[c] =p; } int max=1; int count =0; for (int i = n-1; i >0; --i) { int cur=i; while(cur!=-1) { cur = tree[cur]; count++; } if(count>max) max =count; count=0; } System.out.println(max); } } } //O（n）解   你思路是对的