设计一个自动售货系统，卖soda水的，每份5分钱，只能投进三种1分、2分、5分硬币，要正确的找回钱数。用verilog编程，语法要符合FPGA设计的要求。-Design a vending system, selling soda water, 5 cents each, only dropped three kinds of 1 minute, 2 minutes, 5 coins, money back to the correct number. With verilog programming syntax FPGA design to meet the requirements.