Given a binary tree which has ~N~ nodes, write a program to read the tree data, then print all nodes of the tree in the post order (left, right, root)

Input

• The first line contains the number of nodes of a tree, ~N~ ~(N \le 10^5)~. The nodes are numbered from ~1~ to ~N~. The root of the tree is ~1~.
• The ~i^{th}~ line of the next ~N~ lines contains two integers left and right (left, right ~\le N~), respectively, the left child and the right child of the ~i^{th}~ node. If left is less than or equal to ~0~, node ~i~ has no children on the left. If right is less than or equal to ~0~, node ~i~ has no right child.
• The tree is guaranteed to exists

Output

• All nodes of the tree in the post order, separated by spaces

Example Input

4
2 3
0 4
0 0
0 0

Example Output

4 2 3 1

Hint

class EIUEASPOST
{
    static void Main(string[] args)
    {
        var nNode = NextInt();
        var nodes = ReadTree(nNode);
        // You code here
    }

    static void PrintPostOrder(/*Parameters*/)
    {
    }

    static Node[] ReadTree(int nNode)
    {
        Node[] nodes = new Node[nNode];
        for (var i = 0; i < nNode; i++)
        {
            nodes[i] = new Node(i + 1);
        }
        for (var i = 0; i < nNode; i++)
        {
            var leftIndex = NextInt();
            nodes[i].Left = leftIndex > 0 ? nodes[leftIndex - 1] : null;
            var rightIndex = NextInt();
            nodes[i].Right = rightIndex > 0 ? nodes[rightIndex - 1] : null;
        }
        return nodes;
    }

    class Node
    {
        public int Id;
        public Node Left;
        public Node Right;

        public Node(int id)
        {
            Id = id;
        }
    }
}