Lang:Java
Edit12345678910111213141516171819202122232425262728293031import java.util.ArrayList;import java.util.List;import java.util.Scanner;public class Main {public static void main(String[] args){Scanner in = new Scanner(System.in);int n = in.nextInt(), a, b, expa = 0, expb = 0, expline = 0;int[] tree = new int[n + 1];int[] lineNum = new int[n + 1];tree[1] = 1;for(int i = 1; i <= n; i++){a = in.nextInt();b = in.nextInt();if(tree[b] == 0){tree[b] = a;lineNum[b] = i;}else{expa = a;expb = b;expline = i;if(b == 1){System.out.print(i);return;}}}List<Integer> res = new ArrayList<Integer>();int k = 1;for(; k <= n; k++){