class Matrix:
    # size: a integer represented the size of the square matrix
    # m: the matrix represented in the 2-d list format
    # create a square matrix
    def __init__(self, size, m):
        self.size = size
        self.m = m[:][:]

    # create a new Matrix with the value of current matrix + rhs matrix
    def __add__(self, rhs):
        size = self.size
        return Matrix(size, [[self.m[i][j]+rhs.m[i][j] for j in range(size)] for i in range(size)])

    # create a new Matrix with the value of current matrix - rhs matrix
    def __sub__(self, rhs):
        size = self.size
        return Matrix(size, [[self.m[i][j]-rhs.m[i][j] for j in range(size)] for i in range(size)])

    # create a new Matrix with the value of current matrix * rhs matrix
    def __mul__(self, rhs):
        size = self.size
        m = []
        for i in range(size):
            row = []
            for j in range(size):
                row.append(sum([self.m[i][k]*rhs.m[k][j] for k in range(size)]))
            m.append(row)
        return Matrix(size, m)

    # output format of Matrix
    def __repr__(self):
        return '\n'.join([' '.join(map(str, self.m[i])) for i in range(self.size)])