# trapezium_area_final.py
def addition(x, y):
    return x + y

def divided_by_2(x):
    return x / 2

def main():
    base_line = float(input("밑변의 길이는? "))
    upper_edge = float(input("윗변의 길이는? "))
    height = float(input("높이는? "))

    print("넓이는:", divided_by_2(addition(base_line, upper_edge)) * height)

if __name__ == "__main__":
    main()