input: def linear_eq_objective(a: int, b: int, c: int, x: int, y: int) -> int:
      """ Calculate the objective function of the linear equation of the form ax + by - c.
      Return the value of the objective function.
      >>> linear_eq_objective(3, 5, 7, 1, 1)
      1
      >>> linear_eq_objective(2, 4, 8, 2, 2)
      4
      """
output:     return a * x + b * y - c