Nope, question says The second line contains "n−1 integers p2,p3,…,pn(1≤pi≤n), where pi is the index of the direct superior of the i-th employee." So, in 1 2 1; first number is direct superior of p2 => p1 is direct superior of p2 ; second number is direct superior of p3 => p2 is direct superior of p3 ; third number is direct superior of p4 => p1 is direct superior of p4 ; So, only (3,4) is valid team.