input: def linear_eq(a: int, b: int, c: int, x: int, y: int) -> int:
      """ Calculate the objective function of a linear equation ax + by - c.
      >>> linear_eq(3, 5, 7, 2, 1)
      6
      >>> linear_eq(1, 2, 3, 4, 5)
      11
      """
      return a * x + b * y - c
output:     return a * x + b * y - c