Problem:
 Score : 100 points    Problem Statement 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.      Constraints  1≦a≦100  1≦b≦100  1≦h≦100  All input values are integers.  h is even.         Input The input is given from Standard Input in the following format:  a  b  h       Output Print the area of the given trapezoid. It is guaranteed that the area is an integer.        Sample Input 1 3
4
2      Sample Output 1 7  When the lengths of the upper base, lower base, and height are 3 , 4 , and 2 , respectively, the area of the trapezoid is (3+4)×2/2 = 7 .       Sample Input 2 4
4
4      Sample Output 2 16  In this case, a parallelogram is given, which is also a trapezoid.

Solution (Python):
import math
a, b, h = [int(input()) for i in range(3)]

area = (a + b) * h / 2
print(math.floor(area))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int(((a+b)*h)/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int(h*(a+b)//2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(((a+b)*h)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
area=int((a+b)*h/2)
print(area)

Solution (Python):

import sys

def main(argv=sys.argv):
  
  a = int(input())
  b = int(input())
  h = int(input())
  
  print((a + b) * h // 2)
  
  
  return 0


if __name__ == '__main__':
  sys.exit(main())

Solution (Python):

import sys


def main(argv=sys.argv):

    top = int(input())
    bottom = int(input())
    height = int(input())

    print((top + bottom) * height // 2)

    return 0


if __name__ == '__main__':
    sys.exit(main())

Solution (Python):
print(int((int(input())+int(input()))*int(input())/2))

Solution (Python):

a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
s = (a+b)*h/2
print(int(s))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int(0.5*(a+b)*h))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a,b,h=map(int,open(0).read().split())
print((a+b)*h//2)

Solution (Python):
import math
import queue
import bisect
import heapq
import time
import itertools

mod = int(1e9+7)

def swap(a,b):
    return (b,a)

def gcd(a,b): 
    if (a<b):
        a,b = swap(a,b)
    if (b==0):
        return a
    else:
        return gcd(b,a%b)

def divisors(a): 
    divisors = []
    for i in range(1,int(a**0.5)+1):
        if a%i==0:
            divisors.append(i)
            if i!=a//i:
                divisors.append(a//i)
    return divisors

def is_prime(a): 
    if a<2:
        return False
    elif a==2:
        return True
    elif a%2==0:
        return False
    sqrt_num = int(a**0.5)
    for i in range(3,sqrt_num+1,2):
        if a%i==0:
            return False
    return True

def prime_num(a): 
    pn = [2]
    for i in range(3,int(a**0.5),2):
        prime = True
        for j in pn:
            if i%j==0:
                prime = False
                break
        if prime:
            pn.append(i)
    return pn

def main():
    a = int(input())
    b = int(input())
    h = int(input())
    print(int((a+b)*h/2))
    return

if __name__=='__main__':
    main()

Solution (Python):
a = list(int(input()) for _ in range(3))
print((a[0]+a[1])*a[2]//2)

Solution (Python):
a = input()
b = input()
h = input()
print((a+b)*h/2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a =int(input())
b =int(input())
h =int(input())
print(int((a+b) * h * 0.5))

Solution (Python):
import sys

a = int(input())
b = int(input())
h = int(input())

print(int((a+b) * h / 2))

Solution (Python):
l = [int(input()) for _ in range(3)]

print((l[0] + l[1]) * l[2] //2)

Solution (Python):


a = int(input())
b = int(input())
h = int(input())


m = int((a + b) * h / 2)

print(m)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(((a+b)*h)//2)

Solution (Python):
L=list(int(input()) for _ in range(3))
print((L[0]+L[1])*L[2]//2)

Solution (Python):
a = int(input())
b = int(input())
c = int(input())

print((a+b)*c//2)

Solution (Python):
def solve():
    a = int(input())
    b = int(input())
    h = int(input())
    print((a+b)*h//2)


if __name__ == '__main__':
    solve()

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h*0.5))

Solution (Python):



A = int(input())
B = int(input())
H = int(input())

print(int((A + B) * H / 2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*(h//2))

Solution (Python):
a = int( input() )
b = int( input() ) 
h = int( input() )

print( ( a + b ) * h // 2 )

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int(((a+b)*h)/2))

Solution (Python):
import sys

a, b, h = map(int, sys.stdin.read().split())

def main():
    ans = (a + b) * h // 2
    return ans

if __name__ == '__main__':
    ans = main()
    print(ans)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
 
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int(((a + b) * h) / 2))

Solution (Python):
n, k, x = [int(input()) for i in range(3)]
print((n+k)*x//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a= int(input())
b= int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

ans = (a + b) * h / 2
print(int(ans))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a + b) * h / 2))

Solution (Python):

a, b, h = [int(input()) for _ in range(3)]

print(int((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
c=int(input())

print(int((a+b)*c/2))

Solution (Python):
A = int(input())
B = int(input())
C = int(input())

print('{:.0f}'.format((A+B)*C/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(str((a + b)*h//2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int(((a + b)*h)/2))

Solution (Python):
a,b,h=int(input()),int(input()),int(input())
print(int((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

s = (a + b) * h * 0.5
print(round(s))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

menseki = ( a +b )* h /2

print(int(menseki))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):

si = lambda: input()
ni = lambda: int(input())
nm = lambda: map(int, input().split())
nl = lambda: list(map(int, input().split()))
a = int(input())
b = int(input())
h = int(input())

print(int(((a+b)*h)/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(((a+b)*h)//2)

Solution (Python):
a, b, h = int(input()),int(input()),int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(round((a + b) * h / 2))

Solution (Python):
up = int(input())
down = int(input())
high = int(input())
area = (up + down ) * high / 2
print(int(area))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)/2 * h))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):

a = int(input())
b = int(input())
h = int(input())

menseki = (a+b)*h*0.5
print(int(menseki))

Solution (Python):
from sys import stdin

a = int(stdin.readline().rstrip())
b = int(stdin.readline().rstrip())
h = int(stdin.readline().rstrip())

print((a+b)*h//2)

Solution (Python):





a=int(input())
b=int(input())
h=int(input())
S=(a+b)*h/2
print('%d'%S)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a + b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

S = (a + b) * h // 2

print(S)

Solution (Python):
a=input()
b=input()
h=input()
a=int(a)
b=int(b)
h=int(h)
print (int((a+b)*h/2))

Solution (Python):
a,b,h = [int(input()) for i in range(3)]

m = int((a + b) * h / 2)

print(m)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

n=(a+b)*h//2

print(n)

Solution (Python):
a=input()
b=input()
h=input()
a=int(a)
b=int(b)
h=int(h)
print (int((a+b)*h/2))

Solution (Python):
a=input()
b=input()
h=input()
a=int(a)
b=int(b)
h=int(h)
print (int((a+b)*h/2))

Solution (Python):
a=input()
b=input()
h=input()
a=int(a)
b=int(b)
h=int(h)
print (int((a+b)*h/2))

Solution (Python):
a=input()
b=input()
h=input()
a=int(a)
b=int(b)
h=int(h)
print (int((a+b)*h/2))

Solution (Python):
a=input()
a=int(a)
b=input()
b=int(b)
h=input()
h=int(h)
print(((a+b)*h)//2)

Solution (Python):
a = input()
b = input()
h = input()

a = int(a)
b = int(b)
h = int(h)

print ((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)/2*h))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a + b) * h / 2))

Solution (Python):
a, b, h=map(int, list(input() for i in range(3)))
print((a+b)*h//2)

Solution (Python):
a=int(input());b=int(input());c=int(input());
print((a+b)*c//2)

Solution (Python):


a = int(input())
b = int(input())
h = int(input())
S = int((a+b)*h/2)
print(S)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):

import sys
input = sys.stdin.readline
sys.setrecursionlimit(10**6)

a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
l=[int(input()) for i in range(3)]
a=l[0]
b=l[1]
h=l[2]
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
 
print(int((a+b)*h/2))

Solution (Python):
a, b, h = map(int, open(0).read().split())

def Trapezoids(a, b, h):
    return (a + b) * h // 2

if __name__ == '__main__':
    print(Trapezoids(a, b, h))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):











import sys
sys.setrecursionlimit(10**6)
input=sys.stdin.readline
from math import floor,ceil,sqrt,factorial,log 
from heapq import heappop, heappush, heappushpop
from collections import Counter,defaultdict,deque
from itertools import accumulate,permutations,combinations,product,combinations_with_replacement
from bisect import bisect_left,bisect_right
from copy import deepcopy
inf=float('inf')
mod = 10**9+7
def pprint(*A): 
    for a in A:     print(*a,sep='\n')
def INT_(n): return int(n)-1
def MI(): return map(int,input().split())
def MF(): return map(float, input().split())
def MI_(): return map(INT_,input().split())
def LI(): return list(MI())
def LI_(): return [int(x) - 1 for x in input().split()]
def LF(): return list(MF())
def LIN(n:int): return [I() for _ in range(n)]
def LLIN(n: int): return [LI() for _ in range(n)]
def LLIN_(n: int): return [LI_() for _ in range(n)]
def LLI(): return [list(map(int, l.split() )) for l in input()]
def I(): return int(input())
def F(): return float(input())
def ST(): return input().replace('\n', '')
def main():
    *A, = map(int,open(0).read().split())
    print(sum(A[:2])*A[-1]//2)    
if __name__ == '__main__':
    main()

Solution (Python):
import math
from string import ascii_lowercase

a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
ans = (a+b)*h/2
print(int(ans))

Solution (Python):
a,b,h=map(int,open(0));print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int(((a+b)*h)/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a,b,h=[int(input()) for i in range(3)]
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):


a=int(input())
b=int(input())
h=int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h * 0.5))

Solution (Python):


a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):

import sys, math, itertools, heapq, collections, bisect, fractions
input = lambda: sys.stdin.buffer.readline().rstrip().decode('utf-8')
sys.setrecursionlimit(10**8)
inf = float('inf')
ans = count = 0

a,b,h=[int(input()) for i in range(3)]
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
 
s = (a + b)*h/2
print(int(s))

Solution (Python):
a,b,h = [int(input()) for _ in range(3)]
print(h*(a+b)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
s = int((a + b) * h / 2)
print(s)

Solution (Python):
A, B, H = [int(input()) for _ in range(3)]
print((A+B)*H//2)

Solution (Python):
a = int(input())
b = int(input())
c = int(input())

print(int((a+b)*c/2))

Solution (Python):
a , b , h = [int(input()) for _ in range(3)]
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
def main(a, b, h):
    return (a + b) * h // 2


if __name__ == '__main__':
    A = int(input())
    B = int(input())
    H = int(input())
    print(main(A, B, H))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h//2))

Solution (Python):
a=int(input()) 
b=int(input()) 
h=int(input()) 

print(int((a+b)*h/2))

Solution (Python):


a = int(input()) 
b = int(input()) 
h = int(input()) 

s = int((a + b) * h / 2)
print(s)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
S = int((a + b) * h / 2)
print(S)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(((a+b)*h)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
ans = ((a+b)*h)//2
print(ans)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
ans = ((a+b)*h)//2
print(ans)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):

import sys
input = sys.stdin.readline


A = int(input())
B = int(input())
H = int(input())

print((A+B)*H//2)

Solution (Python):
def examA():
    a = I(); b = I(); h = I()
    ans = (a+b)*h//2
    print(ans)


import sys
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))
def LS(): return sys.stdin.readline().split()
def S(): return sys.stdin.readline().strip()
mod = 10**9 + 7
inf = float('inf')

examA()

Solution (Python):



a = int(input())
b = int(input())
h = int(input())

print( int(((a+b)*h)/2) )

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
 
print(int(h * (a + b) / 2))

Solution (Python):
A = int(input())
B = int(input())
H = int(input())

print(int((A + B)*H//2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

ans = (a + b) * h // 2

print(ans)

Solution (Python):

a=int(input())
b=int(input())
h=int(input())
print(round((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a,b,h=int(input()),int(input()),int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
S = (a+b)*h/2
print(int(S))

Solution (Python):


a = int(input())
b = int(input())
c = int(input())

print(int((a+b)*c/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print('{}'.format( int((a+b)*h/2) ))

Solution (Python):
print((int(input())+int(input()))*int(input())//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
s = (a+b)*h
s = s/2
print(int(s))

Solution (Python):


a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print(int((a+b)*h/2))

Solution (Python):
def solve():
    A, B, H = int(input()), int(input()), int(input())

    return int((A + B) * H / 2)


if __name__ == '__main__':
    res = solve()
    print(res)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print(round((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a+b)*h/2))

Solution (Python):


a = int(input())
b = int(input())
h = int(input())

area = int((a+b)*h/2.0)
print('%d' %(area))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

s = int((a + b) * h / 2)

print(s)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

area = (a + b) * h / 2

print(int(area))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int(((a + b) * h) / 2));

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a, b, h = map(int, [input() for i in range(3)])
print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a+b)*h/2))

Solution (Python):
a,b,h=[int(input()) for _ in range(3)]
print((a+b)*h//2)

Solution (Python):
a, b, h = [int(input()) for _ in range(3)]
print(round((a+b)*h/2))

Solution (Python):
a,b,h = map(int,open(0).read().split())

print((a+b)*h//2)

Solution (Python):
a,b,h  = [int(input()) for  i in range(3)]
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
k = (a+b)*h/2
print(int(k))

Solution (Python):
a = int(input()); b = int(input()); h = int(input())
print((a+b)*h//2)

Solution (Python):
a,b,h=map(int,open(0));print((a+b)*h//2)

Solution (Python):
import math

a = int(input())
b = int(input())
h = int(input())

r = ((a + b) * h) / 2
print(int(r))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

S = (a+b)*h//2

print(S)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
def solve():
    a = int(input())
    b = int(input())
    h = int(input())
    print((a+b)*h//2)

if __name__ == '__main__':
    solve()

Solution (Python):
print((int(input())+int(input()))*int(input())//2)

Solution (Python):
a=int(input());b=int(input());h=int(input())
S=h*(a+b)/2
s=int(S)
print(s)

Solution (Python):
a=int(input());b=int(input());h=int(input())
S=h*(a+b)/2
s=int(S)
print(s)

Solution (Python):
print((int(input())+int(input()))*int(input())//2)

Solution (Python):
a=int(input())
b=int(input())
c=int(input())
print(c*(a+b)//2)

Solution (Python):



a=int(input())
b=int(input())
h=int(input())

print(str(int((a+b)*h/2)))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print((a+b)*h//2)

Solution (Python):
a,b,h = [int(input()) for i in range(3)]
print((a+b)*h//2)

Solution (Python):

a = int(input())
b = int(input())
h = int(input())

ans = (a+b)*h//2

print(ans)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

trapezoid = int((a+b)*h/2)

print(trapezoid)

Solution (Python):
a = int(input().strip())
b = int(input().strip())
h = int(input().strip())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
S = (a + b) * h /2
print(int(S))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print(int((a+b)*h*(1/2)))

Solution (Python):
i = [int(input()) for i in range(3)]
a=i[0]
b=i[1]
h=i[2]
print('{:.0f}'.format((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
if __name__ == "__main__":
    a = int(input())
    b = int(input())
    h = int(input())
    print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b)*h/2))

Solution (Python):
a = int(input())

b= int(input())


c= int(input())
print((a+b)*c//2)

Solution (Python):
a, b, h = [int(input()) for i in range(3)]
print(int((a + b)*h/2))

Solution (Python):
a, b, h = [int(input()) for i in range(3)]
print(int((a + b)*h/2))

Solution (Python):
a, b, h = [int(input()) for i in range(3)]
print(int((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print (((a + b) * h) // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
A = int(input())
B = int(input())
H = int(input())
answer = (H*(A+B)//2)

print(answer)

Solution (Python):
a,b,h=map(int,open(0));print(h*(a+b)//2)

Solution (Python):
a,b,h=int(input()),int(input()),int(input())
print(((a+b)*h)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):



a = int(input())
b = int(input())
h = int(input())


print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int(((a+b)*h/2)))

Solution (Python):
a, b, h = (int(input()) for u in range(3))
print(int((a + b) * h / 2))

Solution (Python):
a, b, h = (int(input()) for u in range(3))
print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
s = (a+b)*h//2
print(s)

Solution (Python):
def resolve():
	a=int(input())
	b=int(input())
	h=int(input())
	print((a+b)*h//2)
resolve()

Solution (Python):
a  =int(input())
b  =int(input())
h  =int(input())

print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
def slove():
    import sys
    input = sys.stdin.readline
    a = int(input().rstrip('\n'))
    b = int(input().rstrip('\n'))
    h = int(input().rstrip('\n'))
    print((a + b) * h // 2)


if __name__ == '__main__':
    slove()

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
import sys

input = sys.stdin.readline


def main():
    a = int(input())
    b = int(input())
    h = int(input())
    print((a + b) * h // 2)


if __name__ == "__main__":
    main()

Solution (Python):
print((int(input())+int(input()))*int(input())//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a,b,h=[int(input()) for i in range(3)];print((a+b)*h//2)

Solution (Python):
a, b, h = [int(input()) for i in range(3)]

s = (a + b)*h /2

print(int(s))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a + b) * h // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

S=(a+b)*h//2

print(S)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

S=(a+b)*h//2

print(S)

Solution (Python):

a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
S = (a+b)*h/2
print(int(S))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int(0.5 * (a + b) * h))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
ans=(a+b)*h/2
print(int(ans))

Solution (Python):
from sys import stdin

a = int(stdin.readline().rstrip())
b = int(stdin.readline().rstrip())
h = int(stdin.readline().rstrip())
s = 0

s = (a+b)*h/2

print(int(s))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(((a+b)*h)//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):


a = int(input())
b = int(input())
h = int(input())

ans = (a + b) * h // 2
print(ans)

Solution (Python):
a, b, h = (int(input()) for _ in range(3))
print(int((a+b)*h/2))

Solution (Python):
import sys
sys.setrecursionlimit(2147483647)
INF=float("inf")
MOD=10**9+7
input=lambda :sys.stdin.readline().rstrip()
def resolve():
    a,b,h=[int(input()) for _ in range(3)]
    print((a+b)*h//2)
resolve()

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
x = lambda: int(input())
print(((x()+x())*x())//2)

Solution (Python):
INT = lambda: int(input())
INTM = lambda: map(int,input().split())
STR = lambda: str(input())
LIST = lambda: list(map(int,input().split()))
def do():
    a = INT()
    b = INT()
    h = INT()
    print(int((a+b)*h/2))
if __name__ == '__main__':
    do()

Solution (Python):


a = int(input())
b = int(input())
h = int(input())

print(((a+b)*h)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
print(int((int(input())+int(input()))*int(input())/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

s = (a+b) * h / 2
print(int(s))

Solution (Python):
input_ = [input() for i in range(3)]

a, b, h = input_

s = int((int(a) + int(b)) * int(h) / 2)

print(s)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
s = (a+b)*h/2
print(int(s))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
ans = (a+b)*h//2
print(ans)

Solution (Python):
a,b,h = map(int,open(0).read().split())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
def resolve():
    a = int(input())
    b = int(input())
    h = int(input())
    print((a + b) * h // 2)


if __name__ == "__main__":
    resolve()

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
ans = int((a + b) * h / 2)
print(ans)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
print((int(input()) + int(input())) * int(input()) // 2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
print((int(input())+int(input()))*int(input())//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print((a+b)*h//2)

Solution (Python):
import sys
input = sys.stdin.readline

def main():
    a = int(input())
    b = int(input())
    h = int(input())

    print((a+b) * h // 2)


if __name__ == "__main__":
    main()

Solution (Python):
a = [int(input()) for i in range(3)]
print(int((a[0]+a[1])*a[2]/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a + b) * h / 2))

Solution (Python):
a,b,h=int(input()),int(input()),int(input()),
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):

a = int(input())
b = int(input())
h = int(input())

print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(h*(a+b)//2)

Solution (Python):
a = int(input())
b = int(input())
c = int(input())
print(int((a+b)*c/2))

Solution (Python):
def main():
  a, b, h = [int(raw_input()) for x in range(3)]
  print(int(0.5*(a+b)*h))

main()

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int((a+b)*h/2))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

print(int((a+b)*h*0.5))

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print(int((a+b)*h/2))

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print(h*(a+b)//2)

Solution (Python):
a = int(input())
b = int(input())
h = int(input())

print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())
print((a+b)*h//2)

Solution (Python):
a=int(input())
b=int(input())
h=int(input())

x=(a+b)*h//2

print(x)

Solution (Python):
a,b,h = (int(input()) for i in range(3))
print((a+b)*h//2)