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

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

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

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

if __name__ == "__main__":
    main()

Solution (Python):

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

print (a+b)*h/2

Solution (Python):




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



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

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

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

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

Solution (Python):
a = int(raw_input())
b = int(raw_input())
h = int(raw_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):

import math
import sys
import itertools
import numpy as np
import functools
import collections
mo = 1000000007
INF = 10**100
r = range

class infix(object):
    def __init__(self, function):
        self.function = function

    def __ror__(self, other):
        self.left = other
        return self

    def __or__(self, other):
        return self.function(self.left, other)

    def __call__(self, value1, value2):
        return self.function(value1, value2)

@infix
def c(f_t_u, f_u_r): return lambda t: f_u_r(f_t_u(t))

class _Ap(object):
    def __rlshift__(self, other):
        self.value = other
        return self

    def __rshift__(self, other):
        return other(self.value)
Ap = _Ap()
ap = Ap







a = input()<<ap>>(int)
b = input()<<ap>>(int)
h = input()<<ap>>(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(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(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 = input()
b = input()
h = 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):
print((int(input())+int(input()))*int(input())//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((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(raw_input())
b = int(raw_input())
h = int(raw_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, 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(raw_input())
b = int(raw_input())
h = int(raw_input())

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

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

Solution (Python):
from collections import defaultdict


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

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

print(D)

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

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

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

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

Solution (Python):
def ini(): return int(input())
def inli(): return list(map(int, input().split()))
def inf(): return float(input())
def inlf(): return list(map(float, input().split()))
def inl(): return list(input())
def pli(): return "".join(list(map(str, ans)))

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

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

S = ( a + b )*h/2

print( int(S) )

Solution (Python):
def ri(): return int(input())
def rli(): return list(map(int, input().split()))
def ris(): return list(input())
def pli(): return "".join(list(map(str, ans)))

a = ri()
b = ri()
h = ri()

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

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

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

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

main()

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

Solution (Python):
import sys

def debug(x, table):
    for name, val in table.items():
        if x is val:
            print('DEBUG:{} -> {}'.format(name, val), file=sys.stderr)
            return None

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

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

    print(ans)

if __name__ == '__main__':
    solve()

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

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

Solution (Python):
import math,string,itertools,fractions,heapq,collections,re,array,bisect,sys,random,time

sys.setrecursionlimit(10**7)
inf = 10**20
mod = 10**9 + 7


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




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

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


if __name__ == '__main__':
    main()

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

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

Solution (Python):



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

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

def main():
	a = int(raw_input())
	b = int(raw_input())
	h = int(raw_input())
	print trapezoid(a, b, h)

main()

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

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

Solution (Python):


N = 3

s = [input() for i in range(N)]

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

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

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

Solution (Python):

a = int(raw_input())
b = int(raw_input())
h = int(raw_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(raw_input())
b=int(raw_input())
h=int(raw_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(round((a + b) * h /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())
daikei = (1/2) * (a + b) * h
print(int(daikei))

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

Solution (Python):

import sys,copy,math,heapq,itertools as it,fractions,re,bisect,collections as coll

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

Solution (Python):
a = int(raw_input())
b = int(raw_input())
h = int(raw_input())
print "{}".format(int((a+b)*h/2))

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 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)*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())

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

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

Solution (Python):



from __future__ import division, print_function, absolute_import, unicode_literals

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

Solution (Python):


from __future__ import print_function
from __future__ import unicode_literals
from __future__ import division
from __future__ import absolute_import
import math
import string
import itertools
import fractions
import heapq
import collections
import re
import array
import bisect

def array2d(d1, d2, init = None):
    return [[init for _ in range(d2)] for _ in range(d1)]

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

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

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())
h=int(input())

print("%s"%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(raw_input())
b = int(raw_input())
h = int(raw_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(raw_input())
b = int(raw_input())
c = int(raw_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(raw_input())
b = int(raw_input())
h = int(raw_input())

s = (a+b)*h/2

print s

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

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

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

Solution (Python):


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

s = (a + b) * h / 2

print s

Solution (Python):

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

Solution (Python):


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

print (a+b)*h/2

Solution (Python):
import sys


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

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

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

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

Solution (Python):
print((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):
n0 = int(input())
n1 = int(input())
n2 = int(input())
print(int( (n0 + n1)  * n2 / 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):
n = int(input())
m = int(input())
l = int(input())
ans = int((n+m)*l/2)
print(ans)

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

Solution (Python):


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

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

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

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

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

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

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

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

print (a+b) * h / 2

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

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

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

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

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

print(area)

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())


area = int(((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())

print(b * h if a == b and b == h else int((a + b) * h / 2))

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

print (a+b)*h/2

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

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

print(ans(a, b, h))

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

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

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

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

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


a = raw_input()
a = int(a)
b = raw_input()
b = int(b)
h = raw_input()
h = int(h)
ans = solve(a, b, h)
print ans

Solution (Python):
from __future__ import division
a = input()
b = input()
h = 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 math as m
from Queue import Queue

class Program:
    
    def main(self):
        a = int(raw_input())
        b = int(raw_input())
        h = int(raw_input())
        
        ans = (a + b) * h * 1 / 2
        print ans
        
if __name__ == '__main__':
    p=Program();
    p.main()

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):
from sys import stdin
a = int(stdin.readline())
b = int(stdin.readline())
h = int(stdin.readline())
print ((a+b)*h)/2

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

print (a+b)*h/2

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

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

print(res)

Solution (Python):
import math

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

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

Solution (Python):
a = int(raw_input())
b = int(raw_input())
h = int(raw_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())

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

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

solve()

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