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-----
3
4
2

-----Sample Output-----
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.

Difficulty: introductory

Starter code:

Solutions:

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

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

# 処理
area = (a + b) * h // 2

# 出力
print(area)

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



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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

answer = (a + b) * h / 2

print(math.ceil(answer))

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

from sys import stdin
input = stdin.readline

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

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

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

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

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

# 045_a
a = int(input())  # 上底の長さ
b = int(input())  # 下底の長さ
h = int(input())  # 高さ

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

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


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

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

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

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

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

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

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

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


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

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

# 台形の面積
# （上底 + 下底）* 高さ / 2

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

# 処理
answer = int((a + b) * h / 2)
print(answer)


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

# 数値の取得
a = int(input())
b = int(input())
h = int(input())
 
# 面積を求めて出力
area = int((a + b) * h / 2)
print(area)

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


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


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


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

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

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

a = int(input())    # 上辺
b = int(input())    # 下辺
h = int(input())    # 高さ

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

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

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

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

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

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

a,b,h=[int(input()) for i in range(0,3)]
print(((a+b)*h//2))


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

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

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

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

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

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

# 上底の長さがa、下底の長さがb、高さがhの台形の面積

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

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


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

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

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

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

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

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


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

a = int(input())
b = int(input())
h = int(input())
print('{:.0f}'.format(h/2*(a+b)))

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

val = [int(input()) for i in range(3)]
print(int((val[0] + val[1]) * val[2] / 2))

import math
from datetime import date

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

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

main()


"""
ABC045 A A - 台形
https://atcoder.jp/contests/abc045/tasks/abc045_a
"""

n = [int(input()) for i in range(3)]

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


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

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

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

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


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

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

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

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

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

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

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


def __starting_point():
    solve()
__starting_point()

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


def __starting_point():
    a = int(input())
    b = int(input())
    h = int(input())
    print((solve(a, b, h)))

__starting_point()

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

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

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

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

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

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

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

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

# import math
# import statistics
# a=input()
#b,c=int(input()),int(input())
# c=[]
# for i in a:
#     c.append(i)
#e1,e2,e3 = map(int,input().split())
#f = list(map(int,input().split()))
#g = [input() for _ in range(a)]
# h = []
# for i in range(e1):
#     h.append(list(map(int,input().split())))

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

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

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

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


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

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

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


def __starting_point():
    iroha()


__starting_point()

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

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

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

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

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

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

print(answer)

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

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

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

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


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

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

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

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

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

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

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


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

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

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

#
# abc045 a
#
import sys
from io import StringIO
import unittest


class TestClass(unittest.TestCase):
    def assertIO(self, input, output):
        stdout, stdin = sys.stdout, sys.stdin
        sys.stdout, sys.stdin = StringIO(), StringIO(input)
        resolve()
        sys.stdout.seek(0)
        out = sys.stdout.read()[:-1]
        sys.stdout, sys.stdin = stdout, stdin
        self.assertEqual(out, output)

    def test_入力例_1(self):
        input = """3
4
2"""
        output = """7"""
        self.assertIO(input, output)

    def test_入力例_2(self):
        input = """4
4
4"""
        output = """16"""
        self.assertIO(input, output)


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


def __starting_point():
    # unittest.main()
    resolve()

__starting_point()

#45
a=int(input())
b=int(input())
h=int(input())
if h%2==0:
    print(int((a+b)*h/2))

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

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


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

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



a=int(input())
b=int(input())
h=int(input())
ans=max(a,b)*h-(abs(b-a)*h//2)
print(ans)

import sys
a, b, h =map(int, sys.stdin.readlines())
print((a+b)*h//2)

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


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

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

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