Find a solution for this math problem: Peter wants to make different sized ice cubes with 32 ounces of water. He can make giant cubes that use 4 ounces per cube, medium cubes that use 2 ounces, and small cubes that use 1/2 an ounce. If he makes 3 giant cubes, 7 medium cubes, and 8 small cubes, how many ounces of water does he have left?