Given a square matrix of size N x N. The task is to rotate it by 90 degrees in anti-clockwise direction without using any extra space. 

Example 1:

Input:
N = 3 
matrix[][] = {{1, 2, 3},
              {4, 5, 6}
              {7, 8, 9}}
Output: 
Rotated Matrix:
3 6 9
2 5 8
1 4 7

Example 2:

Input:
N = 2
matrix[][] = {{1, 2},
              {3, 4}}
Output: 
Rotated Matrix:
2 4
1 3

Your Task:
You dont need to read input or print anything. Complete the function rotateby90() which takes the matrix as input parameter and rotates it by 90 degrees in anti-clockwise direction without using any extra space. You have to modify the input matrix in-place. 

Expected Time Complexity: O(N²)
Expected Auxiliary Space: O(1)

Constraints:
1 ≤ N ≤ 100
1 <= matrix[][] <= 1000