The fitness trainer has the exercise regimen which has swimming, running, and walking. She has no more than twelve hours per week to devote to exercise, having at most four hours running. She wishes to walk at least 3 times as many hours as she swims. Jill will burn on average 528 calories per hour running, 492 calories per hour swimming, and 348 calories per hour walking. How many hours per week must Antonia spend on every exercise to maximize number of calories she burns? Determine maximum number of calories she will burn?