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

Solution (Python):

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

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

Solution (Python):
import sys
import copy
import math
import bisect
import pprint
import bisect
from functools import reduce
from copy import deepcopy
from collections import deque

if __name__ == '__main__':
    a = [int(i) for i in input().split()]
    b = [int(i) for i in input().split()]

    c = [int(i) for i in input().split()]

    print(((a[0]+b[0])*c[0])//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()
print (a+b)*h/2

Solution (Python):
a,b,h=map(int,open(0));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())

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

Solution (Python):

import sys, math, itertools, collections, bisect
input = lambda: sys.stdin.buffer.readline().rstrip().decode('utf-8')
inf = float('inf') ;mod = 10**9+7
mans = inf ;ans = 0 ;count = 0 ;pro = 1

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

Solution (Python):

from sys import stdin
from operator import itemgetter
import math


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())

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

Solution (Python):
a = int(input())
a += int(input())
a *= int(input())
print(a//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())
 
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).read().split())
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):

GBN_DEBUG = False
def dprn(s, i):
    if GBN_DEBUG: print(", " + s + " = " + str(i), end = "")
def dprns(s):
    if GBN_DEBUG: print(", " + s, end = "")
def dprni(i):
    if GBN_DEBUG: print(i, end=" ")
def endl(): 
    if GBN_DEBUG: print('')
def puts(s): print(s)












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)]
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())
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 = [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):

import sys
sys.setrecursionlimit(10**9)
INF=10**18
MOD=10**9+7
def input(): return sys.stdin.readline().rstrip()

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(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):
import sys, re, os
from collections import deque, defaultdict, Counter
from math import ceil, sqrt, hypot, factorial, pi, sin, cos, radians, acos, atan, asin
from itertools import permutations, combinations, product, accumulate
from operator import itemgetter, mul
from copy import deepcopy
from string import ascii_lowercase, ascii_uppercase, digits
from fractions import gcd
def input(): return sys.stdin.readline().strip()
def STR(): return input()
def INT(): return int(input())
def MAP(): return map(int, input().split())
def S_MAP(): return map(str, input().split())
def LIST(): return list(map(int, input().split()))
def S_LIST(): return list(map(str, input().split()))
sys.setrecursionlimit(10 ** 9)
inf = sys.maxsize
mod = 10 ** 9 + 7

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

answer = int(((a + b) * c) / 2)

print(answer)

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())
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*(1/2)))

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))
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)*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('{:0}'.format((a + b) * h // 2))

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

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()) for _ 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):
n= int(input())
n2= int(input())
h = int(input())
result=((n+n2)/2*h)
print(round(result))

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

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

def main():
    mod=10**9+7
    a=I()
    b=I()
    h=I()
    print(((a+b)*h)//2)

main()

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

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

ans = (A[0] + A[1]) * A[2] / 2
print(int(ans))

Solution (Python):

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

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

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, b, h =  [int(input()) 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):
import sys
readline = sys.stdin.buffer.readline

a = int(readline())
b = int(readline())
n = int(readline())

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

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

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

Solution (Python):

import sys

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


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

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

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

Solution (Python):
x=int(input())
y=int(input())
z=int(input())
print(round((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/2))

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

area = (a + b)*h/2

print(int(area))

Solution (Python):









import sys



ipti = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)

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


if __name__ == '__main__':
    main()

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

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

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

Solution (Python):

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

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())
C = int(input())

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

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())

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

Solution (Python):

import sys
INF = float("inf")


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


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))  
    solve(a, b, h)


if __name__ == '__main__':
    main()

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

Solution (Python):
A=[0]*3
for i in range(3):
  A[i]=int(input())

ans=int((A[0]+A[1])*A[2]/2)
print(ans)

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

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

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

Solution (Python):
input = open(0).readline

x = [0]*3
for i in range(3):
    x[i] = int(input().strip())
a, b, h = x[0], x[1], x[2]
ans = int(((a + b) * h)/2)
print(ans)

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

a = int(string_list[0])
b = int(string_list[1])
h = int(string_list[2])

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

print(answer)

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

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

Solution (Python):


from collections import defaultdict

(a, b, h) = [int(input()) for _ in range(0, 3)]

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

Solution (Python):

 
 
def main():
 
    johen = int(input())
    teihen = int(input())
    takasa = int(input())

    print((johen + teihen) * takasa // 2)    
    
    return 0
 
 
if __name__ == '__main__':
    main()

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

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

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( 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())

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

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

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

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

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

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

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

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

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

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

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

Solution (Python):
"""
author : halo2halo
date : 2, Feb, 2020
"""

import sys
import itertools

import numpy as np

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

a,b,h=map(int, read().split())
print(h*(b+a)//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())
c = int(input())

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

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

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

print(menseki)

Solution (Python):


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

Solution (Python):
a = int(input())
b = int(input())
h = int(input())
print(int(1/2*(a+b)*h))

Solution (Python):




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())
c = int(input())

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

area = (a + b) * h / 2

print(int(area))

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

Solution (Python):
def calc_trapezoid_area(top_length, under_length, height):    
    return (top_length + under_length) * height // 2

if __name__=='__main__':
    top_length, under_length, height = map(int, [input() for i in range(3)])
    print(calc_trapezoid_area(top_length, under_length, height))

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

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

Solution (Python):
import sys


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(input())+int(input()))*int(input())//2)

Solution (Python):
def main():
    from sys import stdin, setrecursionlimit
    
    
    
    
    
    
    
    
    
    
    
    
    
    r = [int(stdin.readline()) for i in range(3)]

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

if __name__ == '__main__':
    main()

Solution (Python):
a=int(input(), 10)
b=int(input(), 10)
h=int(input(), 10)

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())

area = (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(int((a+b) * h * 0.5))

Solution (Python):
import sys

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

square = (a + b) * h / 2

print(int(square))

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):
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):
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())

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())
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())
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())

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

print(m)

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

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

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

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

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

Solution (Python):
a = [int(input()) for _ 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())
r = (a + b) / 2 * h

print(int(r))

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((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):
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*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())

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

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

area = (a+b)*h/2

print('{:.0f}'.format(area))

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

Solution (Python):
data = [int(input()) for i in range(3)]
result = (data[0]+data[1])*data[2]*0.5
if result == int(result) :
  print(int(result))
else :
  print(result)

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

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