Write a program that prints the maximum element of a square matrix below the main diagonal. The elements of the main diagonal are also taken into account.

def max_below_main_diagonal(matrix):
  maximum = matrix[0][0]
  for row in range(1, len(matrix)):
    for col in range(row+1):
      if matrix[row][col] > maximum:
        maximum = matrix[row][col]
  return maximum