In mathematics, particularly in linear algebra,
a skew-symmetric matrix (also known as an antisymmetric or antimetric) is a square matrix **A** which is transposed
and negative.
This means that it satisfies the equation
A = −A^{T}.
If the entry in the i-th row and j-th column is a_{ij}, i.e.
A = (a_{ij})
then the symmetric condition becomes
a_{ij} = −a_{ji}.

You should determine whether the specified square matrix is skew-symmetric or not.

You can find more details on Skew-symmetric matrices on its Wikipedia page.

**Input: ** A square matrix as a list of lists with integers.

**Output: ** If the matrix is skew-symmetric or not as a boolean.

**Example:**

checkio([ [ 0, 1, 2], [-1, 0, 1], [-2, -1, 0]]) == True checkio([ [ 0, 1, 2], [-1, 1, 1], [-2, -1, 0]]) == False checkio([ [ 0, 1, 2], [-1, 0, 1], [-3, -1, 0]]) == False

**How it is used: **
Skew-symmetric matrices can be useful for the cross product, mathematical operations which are used for the calculation of force movements.
Matrixes are the basis of linear algebra and vector graphics.

**Precondition:** 0 < N < 5