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):
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())
result=.5*(a+b)*h
print("%d"%result)

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

Solution (Python):
import sys, os, math, bisect, itertools, collections, heapq, queue

from decimal import Decimal
from collections import defaultdict, deque

sys.setrecursionlimit(10000000)

ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]

iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]

lcm = lambda x, y: (x * y) // math.gcd(x, y)

MOD = 10 ** 9 + 7
MAX = float('inf')


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")

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


if __name__ == '__main__':
    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(h * (a+b)//2)

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

Solution (Python):
import sys


def getN():
    return int(input())


def getNM():
    return map(int, input().split())


def getList():
    return list(map(int, input().split()))


def input():
    return sys.stdin.readline().rstrip()





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

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

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


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

Solution (Python):

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


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

Solution (Python):
def atcoderA():
    n = []
    for i in range(3):
        n.append(input())
    print(int((int(n[0])+int(n[1]))*int(n[2])/2))

atcoderA()

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

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

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 = lambda a, b, h: int((a+b)*h/2)
print(x(a, b, h))

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

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

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

Solution (Python):

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

s=(a+b)*c*1/2
print(int(s))

Solution (Python):
from fractions import gcd
from collections import Counter, deque, defaultdict
from heapq import heappush, heappop, heappushpop, heapify, heapreplace, merge
from bisect import bisect_left, bisect_right, bisect, insort_left, insort_right, insort
from itertools import accumulate, product, permutations, combinations

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

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

if __name__ == '__main__':
    main()

Solution (Python):



def main():
    a = int(input())
    b = int(input())
    h = int(input())
    s = (a + b) * h >> 1
    return s


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

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




ans = (a + b)*h/2


ans_int = int(ans) 
print(ans_int)

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

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

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

print(actual(a, b, h))

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

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

print(menseki)

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

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

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

    square = a * h
    triangle = ((b - a) * h) //2
    print(square + triangle)
main()

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

A=int(int(a)+int(b))
B=int(int(A)*int(h)/2)

print(int(B))

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

area()

Solution (Python):

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

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

Solution (Python):


def read_int():
    return int(input().strip())


def read_ints():
    return list(map(int, input().strip().split(' ')))


def solve():
    a = read_int()
    b = read_int()
    h = read_int()
    return (a+b)*h//2


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

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

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

Solution (Python):
a, b, h = map(int, open(0).read().split())
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,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):
l = [int(input()) for _ in range(3)]
a,b,h = l[0],l[1],l[2]

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

Solution (Python):
import sys
import numpy as np
import random
from decimal import Decimal
import itertools
import re
import bisect
from collections import deque, Counter
from functools import lru_cache

sys.setrecursionlimit(10**9)
INF = 10**13
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def I(): return int(sys.stdin.buffer.readline())
def LS(): return sys.stdin.buffer.readline().rstrip().decode('utf-8').split()
def S(): return sys.stdin.buffer.readline().rstrip().decode('utf-8')
def IR(n): return [I() for i in range(n)]
def LIR(n): return [LI() for i in range(n)]
def SR(n): return [S() for i in range(n)]
def LSR(n): return [LS() for i in range(n)]
def SRL(n): return [list(S()) for i in range(n)]
def MSRL(n): return [[int(j) for j in list(S())] for i in range(n)]
def SERIES(n): return np.fromstring(sys.stdin.buffer.read(), dtype=np.int32, sep=' ')
def GRID(h,w): return np.fromstring(sys.stdin.buffer.read(), dtype=np.int32, sep=' ').reshape(h,-1)[:,:w]
def GRIDfromString(h,w): return np.frombuffer(sys.stdin.buffer.read(), 'S1').reshape(h,-1)[:,:w]
MOD = 1000000007

def main():
	a, b, h = IR(3)
	print((a+b)*h//2)

if __name__ == '__main__':
    main()

Solution (Python):
'''     
        
        
        

import sys
import math


def get_ints(): return map(int, input().strip().split())
def get_list(): return list(get_ints())

def printspx(*args): return print(*args, end="")
def printsp(*args): return print(*args, end=" ")
def printchk(*args): return print(*args, end=" \ ")

MODPRIME = int(1e9+7); BABYMODPR = 998244353;

ONLINE_JUDGE = 1
if not ONLINE_JUDGE:
    sys.stdin  = open("input.txt","r")
    sys.stdout = open("output.txt","w")
    sys.stderr = open("output.txt","w")


a = int(input())
b = int(input())
h = int(input())
print(((a+b)*h)//2)
'''
>>> COMMENT THE STDIN!! CHANGE ONLINE JUDGE !!
THE LOGIC AND APPROACH IS BY ME @luctivud ( UDIT GUPTA )
SOME PARTS OF THE CODE HAS BEEN TAKEN FROM WEBSITES LIKE::
(I Own the code if no link is provided here or I may have missed mentioning it)
DO NOT PLAGIARISE.
TESTCASES:
>>> COMMENT THE STDIN!! CHANGE ONLINE JUDGE !!
'''

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*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( 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)/2*h))

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

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())

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

print(int(ans))

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

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

Solution (Python):
import sys
def I(): return int(sys.stdin.readline().rstrip())
a,b,h = [I() for _ 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):
import sys

def ans(a, b, h) :
  return int((1 / 2) * (a + b) * h)

lis = list()

for line in sys.stdin : 
  lis.append(int(line))
  
print(ans(lis[0], lis[1], lis[2]))

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

Solution (Python):

import sys


def solve(a: int, b: int, h: int):
    res = (a + b) * h / 2
    return int(res)



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word

    tokens = iterate_tokens()
    a = int(next(tokens))  
    b = int(next(tokens))  
    h = int(next(tokens))  
    print(solve(a, b, h))


if __name__ == "__main__":
    main()

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())
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())

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

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

Solution (Python):
top=int(input())
bottom=int(input())
height=int(input())
 
num=top+bottom
 
ans=int(num*height/2)
 
print(str(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(int((a+b)*h/2))

Solution (Python):

a = input()

b = input()

h = input()

ans = 0


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


print(round(ans))

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())

area = (a+b)*h/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())
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())

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())
c = int(input())
d = 0
e = 0
d = a + b
e = d * c // 2
print(e)

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

Solution (Python):
N=int(input())
K=int(input())
X=int(input())
print((N+K)*X//2)

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

s = 0
if 1 <= a <= 100 and 1 <= b <= 100 and 1 <= h <= 100 and h % 2 == 0:
  s = (a + b) * h / 2
  print(int(s))

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):
l = [int(input()) for i in range(3)]
print(int((l[0] + l[1]) * l[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())

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

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

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

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

Solution (Python):
import sys
import math
 
sys.setrecursionlimit(10 ** 8)
input = sys.stdin.readline
 
def main():
  a = int(input())
  b = int(input())
  h = int(input())
  
  print(int((a+b)*h/2))
    
if __name__ == '__main__':
    main()

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

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

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

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

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())

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

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

Solution (Python):

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

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

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

Solution (Python):
import sys
import heapq, math
from itertools import zip_longest, permutations, combinations, combinations_with_replacement
from itertools import accumulate, dropwhile, takewhile, groupby
from functools import lru_cache
from copy import deepcopy

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

print("{}".format(S))

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

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

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

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

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

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

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

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

Solution (Python):
a,b,h = (int(input()) for _ in [0]*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):
x = int(input())
y = int(input())
z = int(input())
print(int((x+y)*z/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 * 0.5))

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

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

Solution (Python):
from sys import stdin

def I(): return int(stdin.readline().rstrip())

a,b,h = [I() for i in range(3)]

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

print(ans)

Solution (Python):
top, bottom, height = [int(input()) for i in range(3)]
result = (top + bottom) * height // 2
print(result)

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

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

Solution (Python):



import sys


def input():
    return sys.stdin.readline()


def resolve():
    a = int(input().rstrip())
    b = int(input().rstrip())
    h = int(input().rstrip())

    s = (a+b)*h / 2

    print(int(s))


if __name__ == "__main__":
    resolve()

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

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

Solution (Python):
"""
N = list(map(int,input().split()))
S = [str(input()) for _ in range(N)]
S = [list(map(int,list(input()))) for _ in range(h)] 
print(*S,sep="")
"""

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

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

Solution (Python):


import sys






















def main():
    mod = 1000000007                
    inf = float('inf')              
    
    sys.setrecursionlimit(10**6)    
    def input(): return sys.stdin.readline().rstrip()
    def ii():    return int(input())
    def mi():    return map(int, input().split())
    def mi_0():  return map(lambda x: int(x)-1, input().split())
    def lmi():   return list(map(int, input().split()))
    def lmi_0(): return list(map(lambda x: int(x)-1, input().split()))
    def li():    return list(input())
    
    
    a = ii()
    b = ii()
    h = ii()
    print((a + b) * h // 2)


if __name__ == "__main__":
    main()

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

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

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

Solution (Python):

"""
Created on Fri May 15 12:41:57 2020

@author: shinba
"""

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

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

main()

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

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

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

a = params[0]
b = params[1]
h = params[2]

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

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

Solution (Python):
import sys
from itertools import permutations

def solve():
    input = sys.stdin.readline
    a = int(input())
    b = int(input())
    h = int(input())
    print((a + b) * h // 2)
    return 0

if __name__ == "__main__":
    solve()

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


if __name__ == '__main__':
    main()

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

Solution (Python):
import sys
def input(): return sys.stdin.readline().strip()

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

if __name__ == "__main__":
  resolve()

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):
import sys
input = sys.stdin.readline

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

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

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

Solution (Python):
from collections import deque
from heapq import heapify,heappop,heappush,heappushpop
from copy import copy,deepcopy
from itertools import product,permutations,combinations,combinations_with_replacement
from collections import defaultdict,Counter
from bisect import bisect_left,bisect_right


from functools import reduce
from pprint import pprint

INF = float("inf")

def myinput():
    return map(int,input().split())

def mylistinput(n):
    return [ list(myinput()) for _ in range(n) ]

def mycol(data,col):
    return [ row[col] for row in data ]

def mysort(data,col,reverse_flag):
    data.sort(key=lambda x:x[col],reverse=reverse_flag)
    return data

def mymax(data):
    M = -1*float("inf")
    for i in range(len(data)):
        m = max(data[i])
        M = max(M,m)
    return M

def mymin(data):
    m = float("inf")
    for i in range(len(data)):
        M = min(data[i])
        m = min(m,M)
    return m

def mycount(ls,x):
    
    l = bisect_left(ls,x)
    r = bisect_right(ls,x)
    return (r-l)

def myoutput(ls,space=True):
    if space:
        if len(ls)==0:
            print(" ")
        elif type(ls[0])==str:
            print(" ".join(ls))
        elif type(ls[0])==int:
            print(" ".join(map(str,ls)))
        else:
            print("Output Error")
    else:
        if len(ls)==0:
            print("")
        elif type(ls[0])==str:
            print("".join(ls))
        elif type(ls[0])==int:
            print("".join(map(str,ls)))
        else:
            print("Output Error")

def I():
    return int(input())

def MI():
    return map(int,input().split())

def RI():
    return list(map(int,input().split()))

def CI(n):
    return [ int(input()) for _ in range(n) ]

def LI(n):
    return [ list(map(int,input().split())) for _ in range(n) ]

def S():
    return input()

def MS():
    return input().split()

def RS():
    return list(input().split())

def CS(n):
    return [ input() for _ in range(n) ]

def LS(n):
    return [ list(input().split()) for _ in range(n) ]

a = I()
b = I()
h = I()

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

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

Solution (Python):
from sys import exit
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((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):
s = [int(input()) for i in range(3)]
print(int((s[0]+s[1])*s[2]/2))

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

Solution (Python):






import sys
input = sys.stdin.readline

import math
from collections import deque
from fractions import gcd
from functools import lru_cache






MOD = 10**9+7
INF = float('inf')






def inputI(): return int(input().strip())
def inputS(): return input().strip()
def inputIL(): return list(map(int,input().split()))
def inputSL(): return list(map(str,input().split()))
def inputILs(n): return list(int(input()) for _ in range(n))
def inputSLs(n): return list(input().strip() for _ in range(n))
def inputILL(n): return [list(map(int, input().split())) for _ in range(n)]
def inputSLL(n): return [list(map(str, input().split())) for _ in range(n)]


def inv(n): return pow(n, MOD-2, MOD)


kaijo_memo = []
def kaijo(n):
  if(len(kaijo_memo) > n):
    return kaijo_memo[n]
  if(len(kaijo_memo) == 0):
    kaijo_memo.append(1)
  while(len(kaijo_memo) <= n):
    kaijo_memo.append(kaijo_memo[-1] * len(kaijo_memo) % MOD)
  return kaijo_memo[n]

gyaku_kaijo_memo = []
def gyaku_kaijo(n):
  if(len(gyaku_kaijo_memo) > n):
    return gyaku_kaijo_memo[n]
  if(len(gyaku_kaijo_memo) == 0):
    gyaku_kaijo_memo.append(1)
  while(len(gyaku_kaijo_memo) <= n):
    gyaku_kaijo_memo.append(gyaku_kaijo_memo[-1] * pow(len(gyaku_kaijo_memo),MOD-2,MOD) % MOD)
  return gyaku_kaijo_memo[n]

def nCr(n,r):
  if(n == r):
    return 1
  if(n < r or r < 0):
    return 0
  ret = 1
  ret = ret * kaijo(n) % MOD
  ret = ret * gyaku_kaijo(r) % MOD
  ret = ret * gyaku_kaijo(n-r) % MOD
  return ret


def factorization(n):
    arr = []
    temp = n
    for i in range(2, int(-(-n**0.5//1))+1):
        if temp%i==0:
            cnt=0
            while temp%i==0:
                cnt+=1
                temp //= i
            arr.append([i, cnt])
    if temp!=1:
        arr.append([temp, 1])

    if arr==[]:
        arr.append([n, 1])
    return arr


def lcm(a, b):
    return a * b // gcd (a, b)





a,b,h = inputILs(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((a + b) * h // 2)

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

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

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