Carl cleans offices. He has the following buildings to clean every day: building A, which is 12,500 square feet; building B, which is 24,500 square feet; building C, which is 10,500 square feet; and building D, which is 6,700 square feet. He is allowed 5 seconds per square foot. Each employee is allowed one 30-minute lunch per shift. How many employees will he need to hire?