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EIUEASPOST - Postorder

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 (0 <N ≤ 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 ≤ 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
Output:
4 2 3 1

Gợi ý

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;
        }
    }
}

Added by:Ha Minh Ngoc
Date:2017-12-10
Time limit:1s-1.100s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
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