Read problem statements in [Mandarin Chinese] and [Bengali].

Given n (n is even), determine the number of black cells in an n \times n chessboard. 

------ Input Format ------ 

The only line of the input contains a single integer n.

------ Output Format ------ 

Output the number of black cells in an n \times n chessboard.

------ Constraints ------ 

$2 ≤ n ≤ 100$
$n$ is even

----- Sample Input 1 ------ 
8
----- Sample Output 1 ------ 
32
----- explanation 1 ------ 

There are $32$ black cells and $32$ white cells in an $8 \times 8$ chessboard. So the answer is $32$.

Difficulty: EASY

Solutions:
n = int(input())
print(pow(n, 2) // 2)


n = int(input())
print(n * n // 2)


n = int(input())
if n % 2 == 0:
	print(n * n // 2)


board = int(input())
black_cell_for_row = board / 2
black_cell = black_cell_for_row * board
print(int(black_cell))


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


n = int(input())
c = n ** 2
print(c // 2)


n = int(input())
a = n ** 2
b = a // 2
print(b)


t = int(input())
print(int(t ** 2 / 2))


n = int(input())
res = n * n
op = res // 2
print(op)


x = int(input())
print(x * x // 2)


n = int(input())
m = n * n
print(m // 2)


n = int(input())
r = n // 2
n = n * r
print(n)


def cell(n):
	b = n * n
	return int(b / 2)
n = int(input())
v = cell(n)
print(v)


n = int(input())
black = n * n // 2
print(black)


N = int(input())
print(N * N // 2)


t = int(input())
x = t // 2
print(x * t)


a = int(input())
print(a ** 2 // 2)


n = int(input())
a = n * n
q = a // 2
print(q)