input: def compute_objective(a: int, b: int, c: int, x: int, y: int) -> int:
      """Calculate the objective function of a linear equation in the form ax + by = c.
      >>> compute_objective(3, 5, 7, 1, 1)
      -1
      >>> compute_objective(3, 5, 7, 2, 1)
      0
      """
      return a*x + b*y - c
output:     return a*x + b*y - c