You are given a trapezoid. The lengths of its upper base, lower base, and height are a, b, and h, respectively.    An example of a trapezoid  Find the area of this trapezoid.
#!/usr/bin/env python3
def main():
  a = [int(input()) for i in range(3)]
  print((a[0]+a[1])*a[2]/2)

if __name__=='__main__':main()

#!/usr/bin/env python3
def main():
  a = [int(input()) for i in range(3)]
  print(int((a[0]+a[1])*a[2]/2))

if __name__=='__main__':main()