text: # Problem You are given a tree (a graph with n vertices and n - 1 edges in which it's possible to reach any vertex from any other vertex using only its edges).A vertex can be destroyed if this vertex has even degree.If you destroy a vertex, all edges connected to it are also deleted.Destroy all vertices in the given tree or determine that it is impossible.Input The first line contains integer n (1 ≤ n ≤ 2·105) — number of vertices in a tree.The second line contains n integers p1, p2, ..., pn (0 ≤ pi ≤ n).If pi ≠ 0 there is an edge between vertices i and pi.It is guaranteed that the given graph is a tree.Output If it's possible to destroy all vertices, print "YES" (without quotes), otherwise print "NO" (without quotes).If it's possible to destroy all vertices, in the next n lines print the indices of the vertices in order you destroy them.If there are multiple correct answers, print any.Examples Input 5 0 1 2 1 2 Output YES 1 2 3 5 4 Input 4 0 1 2 3 Output NO Note In the first example at first you have to remove the vertex with index 1 (after that, the edges (1, 2) and (1, 4) are removed), then the vertex with index 2 (and edges (2, 3) and (2, 5) are removed).After that there are no edges in the tree, so you can remove remaining vertices in any order.<image> # Solution import java.io.OutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintWriter; import java.util.List; import java.io.BufferedWriter; import java.io.Writer; import java.io.OutputStreamWriter; import java.util.InputMismatchException; import java.io.IOException; import java.util.ArrayList; import java.io.InputStream; /** * Built using CHelper plug-in * Actual solution is at the top * * @author The Viet Nguyen */ public class Main { public static void main(String[] args) { InputStream inputStream = System.in; OutputStream outputStream = System.