40. Write a Structured Text program that count the available space in a parking lot with a capacity 100 spaces. The parking lot has two sensers, and two Light Indicators. The first sensor is mounted t the entrance and the second sensor is mounted at the exit. There is a green light that indicates that there is still available space left in the parking lot, and a red light that indicates that the parking lot is full. Don't use any library function except R_TRIG if needed: [10 pts]