Level order traversal

For a given a Binary Tree of type integer, print it in a level order fashion where each level will be printed on a new line. Elements on every level will be printed in a linear fashion and a single space will separate them.

Example:

For the above-depicted tree, when printed in a level order fashion, the output would look like:

10
20 30 
40 50 60
Where each new line denotes the level in the tree.

Input Format:

The first and the only line of input will contain the node data, all separated by a single space. Since -1 is used as an indication whether the left or right node data exist for root, it will not be a part of the node data.

Output Format:

The given input tree will be printed in a level order fashion where each level will be printed on a new line. 
Elements on every level will be printed in a linear fashion. A single space will separate them.

Constraints:

1 <= N <= 10^5
Where N is the total number of nodes in the binary tree.

Time Limit: 1 sec

Sample Input 1:

10 20 30 40 50 -1 60 -1 -1 -1 -1 -1 -1 

Sample Output 1:

10 
20 30 
40 50 60 

Sample Input 2:

8 3 10 1 6 -1 14 -1 -1 4 7 13 -1 -1 -1 -1 -1 -1 -1

Sample Output 2:

8 
3 10 
1 6 14 
4 7 13