Find the number of ways to choose a pair of an even number and an odd number from the positive integers between 1 and K (inclusive). The order does not matter.

-----Constraints-----
 - 2\leq K\leq 100
 - K is an integer.

-----Input-----
Input is given from Standard Input in the following format:
K

-----Output-----
Print the number of ways to choose a pair of an even number and an odd number from the positive integers between 1 and K (inclusive).

-----Sample Input-----
3

-----Sample Output-----
2

Two pairs can be chosen: (2,1) and (2,3).

Difficulty: introductory

Starter code:

Solutions:
n=int(input())
odd=(n+1)//2
even=n//2
print(odd*even)

k=int(input())

if k%2==0:
    ans=(k//2)*(k//2)
else:
    ans= ((k-1)//2)*((k+1)//2)

print(ans)

k = int(input())
print(((k//2)**2 if k % 2 == 0 else (k//2) * (k//2+1)))


K = int(input())
print(K // 2 * (K - K // 2))

a = int(input())
odd = 0
even = 0
for i in range(1, a+1):
  if i%2 == 1:
    odd += 1
  if i%2 == 0:
    even += 1

print(odd*even)  

s = int(input())
print((s-s//2) * (s//2))

k = int(input())
if k % 2 == 0:
    print(k//2 * k//2)
else:
    print(k//2 * (k//2+1))

k = int(input())
s = 0
for x in range(1, k + 1):
  for y in range(1, k + 1):
    if y % 2 == 1 and x % 2 == 0:
      s = s + 1
print(s)


import math
k=int(input())
print(k//2*(math.ceil((k/2))))

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

K = int(input())

cnt= 0
for i in range(K, 1, -1):
    for _ in range(i-1, 0, -2):
        cnt += 1
print(cnt)

k = int(input())
a = 0
b = 0
for i in range(1, k+1):
    if i%2 == 0:
        a += 1
    else:
        b += 1
print(a*b)

k=int(input())

if k%2==0:
    ans=(k//2)**2
else:
    ans=(k//2)*(k//2+1)
    
print(ans)

k =int(input())
odd_num = (k-1)//2 +1
even_num = k//2
print(((odd_num)*(even_num)))


k = int(input())
if k%2 == 0:
    print((k//2)**2)
else:
    print((k//2)*((k//2)+1))

K = int(input())
if K % 2 == 0:
    print(int(K*K/4))
else:
    print(int((K+1)*(K-1)/4))

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


import sys

K = int(sys.stdin.readline())
print((K - K // 2) * (K // 2))

K = int(input())

print((K // 2) * (K - (K // 2)))

k=int(input())
if k%2==0:
    print(k**2//4)
else:
    print((k//2)*(k+1)//2)

k = int(input())
e = k // 2
o = k - e
print(e * o)

K = int(input())

print((K // 2) * (K - K // 2))

K = int(input())
print((K//2*(K-K//2)))



n = int(input())
if n % 2 == 0:
  print((n // 2) ** 2)
else:
  print((n // 2) * (n // 2 + 1))

K = int(input())

print(K//2*(K-K//2))

k = int (input ())
if k%2 == 0:
  print (round((k**2)/4))
else:
  kk = (k//2)+1
  kg = k//2
  print (kk*kg)

k=int(input())
if k%2!=0:
    print(((k-1)*(k+1)//4))
else:
    print((k**2//4))


k=int(input())
even=k//2
odd=k-even
print(even*odd)

#from statistics import median
#import collections
#aa = collections.Counter(a) # list to list || .most_common(2)で最大の2個とりだせるお a[0][0]
from math import gcd
from itertools import combinations,permutations,accumulate, product # (string,3) 3回
#from collections import deque
from collections import deque,defaultdict,Counter
import decimal
import re
import math
import bisect
import heapq
#
#
#
# pythonで無理なときは、pypyでやると正解するかも！！
#
#
# my_round_int = lambda x:np.round((x*2 + 1)//2)
# 四捨五入g
#
# インデックス系
# int min_y = max(0, i - 2), max_y = min(h - 1, i + 2);
# int min_x = max(0, j - 2), max_x = min(w - 1, j + 2);
#
#
import sys
sys.setrecursionlimit(10000000)
# mod = 10**9 + 7
#mod = 9982443453
mod = 998244353
INF = float('inf')
from sys import stdin
readline = stdin.readline
def readInts():
  return list(map(int,readline().split()))
def readTuples():
    return tuple(map(int,readline().split()))
def I():
    return int(readline())
k = I()
odd = 0
even = 0
if k%2:
    odd = k//2 + 1
else:
    odd = k//2
even = k//2
print((odd * even))


K = int(input())
ans = 0
for i in range(1, K + 1, 2):
    for j in range(2, K + 1, 2):
        ans += 1
print(ans)


a = int(input())
b = []
c = []
x = 0
for i in range(a):
    if (i + 1) % 2 == 1:
        b.append(i + 1)
    else:
        c.append(i + 1)
for i in range(len(b)):
    x = x + len(c)
print(x)

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

n = int(input())
print((n // 2) * ((n + 1)// 2))

a = int(input())
print((a // 2) * ((a+1) // 2))

n = int(input())
m = n % 2
o = n //2

if m ==1:
    print(o*(o+1))
else:
    print(o*o)

from itertools import combinations


def main():
    n = int(input())

    ans = 0
    for a, b in (list(combinations(range(1, n+1), 2))):
        if (a%2==0 and b%2 != 0) or (b%2==0 and a%2!=0):
            ans += 1

    print(ans)


main()

k = int(input())
l = k//2
r = k-l
print(l*r)

k=int(input())
h=k//2
if k%2==1:
  print(h*(h+1))
else:
  print(h**2)

K = int(input())
a = int(K / 2)
if K % 2 == 0:
  print((a * a))
else:
  print((a * (a + 1)))
  


a=int(input())
if a%2==0:
  ans=int((a/2)**2)
else:
  ans=int(((a-1)/2)*((a+1)/2))
print(ans)

k = int(input())
if k%2==0:print(k**2//4)
else:print((k-1)**2//4+(k-1)//2)


a=int(input())
if a%2==0:
    print((a//2)*(a//2))
else:
    print((a//2)*((a//2) +1))

k = int(input())
if k%2 == 0:
  print(int(k**2/4))
else:
  print(int((k**2-1)/4))

K=int(input())
print(((K//2)*((K-1)//2+1)))


N = int(input())

if N & 1:
  print((N // 2 + 1) * (N // 2))
else:
  print((N // 2) ** 2)

K = int(input())
odd = 0
even = 0
for i in range(1, K+1):
    if i%2 == 0:
        even += 1
    else:
        odd +=1
print(odd*even)

k = int(input())
a = k//2
b = k-a
print(a*b)

K = int(input())

even = K // 2
odd = K - even
if K == 3:
  print(2)
else:
  print(even * odd)

n = int(input())
if n%2==0:
    print((n//2)**2)
else:
    print((n//2)*(n//2+1))

k=int(input())
if k%2==0:
    print((k//2)**2)
else:
    print((k//2+1)*(k//2))

K = int(input())
e = K // 2
o = (K+1)//2
print((e*o))


k = int(input())

if k % 2 == 0:
  print((k//2) * (k//2))
else:
  print((k//2)*(k//2++1))

N = int(input())
A = N//2
B = N-A
print(A*B)

n=int(input())
if n%2==1:
    print((n//2)*(n//2+1))
else:
    print((n//2)**2)

# ABC108
# A Pair
import math
K = int(input())
if K % 2:
    ans = (K//2+1) * (K//2)
else:
    ans = (K//2) * (K//2)
pass
print(ans)


K = int(input())
print((K//2)**2 if K%2==0 else (K//2) * (K//2+1))

K = int(input())

e_n = K // 2
o_n = K - e_n

print(e_n * o_n)

K=int(input())
print(K//2*(K//2+K%2))

K = int(input())
num1 = K // 2
num2 = K - num1
print(int(num1*num2))

n = int(input())
print(n // 2 * ((n + 1) // 2))

k = int(input())
c = k // 2
print(c * (k - c))

n=int(input())
m=n//2
if n%2==1:
  print(m*(m+1))
else:
  print(m**2)

k = int(input())
if k%2==0:
    print((k//2)**2)
else:
    print((k//2)*(k//2+1))

k=int(input())
if k%2==0:
  ans=(k//2)**2
else:
  ans=(k//2)*(k//2+1)
print(ans)

def main():
    K = int(input())
    oddnum = K//2
    evennum = K//2 + K%2
    ans = oddnum*evennum
    return ans
print((main()))


K = int(input())
count = 0

print((K//2)*((K+1)//2))

n = int(input())
if n % 2 == 0:
  print((n**2)//4)
else:
  print(((n-1)//2) * ((n+1) // 2))

k = int(input())
print((k//2)*((k+1) //2))

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

k = int(input())
if k % 2 == 0:
    print((k // 2) ** 2)
else:
    print((k // 2) * (k + 1) // 2)

k=int(input())
print((k//2)**2 if k&1!=1 else (k+1)//2 * ((k+1)//2-1))

K = int(input())
a = K//2
b = (K+1)//2
print((a*b))


num = int(input())

even_count = num // 2

if num % 2 == 0:
    odd_count = even_count
else:
    odd_count = even_count + 1

print((odd_count * even_count))


k = int(input())

if k % 2 == 0:
    print(((k // 2) ** 2))
else:
    print(((k // 2 + 1) * (k // 2)))


k = int(input())
print(int((k/2)**2 if k%2==0 else (k//2)*((k//2)+1)))

K = int(input())
print((K//2*((K+1)//2)))


K=int(input())
sum=0
i=1
while i<=K:
    i+=2
    j=2
    while j<=K:
        j+=2
        sum+=1
print(sum)

n = int(input())
m = n//2
if n % 2 ==1:
  print(m*(m+1))
elif n % 2 ==0:
  print(m**2)

K = int(input())
m = K//2
if K%2:
    print(m * (m+1))
else:
    print(m * m)

from math import ceil
k = int(input())
print(k//2*ceil(k/2))

k = int(input())

cnt = 0
for i in range(1, k+ 1):
    for j in range(2, k + 1):
        if i % 2 == 1 and j % 2 == 0:
            cnt += 1

print(cnt)

a=input()
a=int(a)
if a%2==0:
  print((int((a/2)**2)))
else:
  print((int(a/2)*(int(int(a/2)+1))))


K = int(input())
if K % 2 == 0:
    ans = (K//2)*(K//2)
else:
    K -= 1
    ans = (K//2)*(K//2+1)
print(ans)


k = int(input())
odd = k // 2
print(odd * (k - odd))

K = int(input())
if K % 2 != 0:
    odd = int((K+1)/2)
    even = int((K-1)/2)
else:
    odd = int(K/2)
    even = int(K/2)
print(odd * even)

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



K = int(input())

print((K>>1)*((K+1)>>1))

K = int(input())
odd = 0
even = 0
for i in range(1,K+1):
  if i % 2 == 0:
    odd += 1
  else:
    even += 1

print(odd * even)

k = int(input())
if k % 2 == 0:
    e = k//2
    o = k//2
else:
    e = k//2
    o = k//2+1
print(e*o)

k = int(input())

if k % 2 == 0:
    ans = (k / 2) ** 2
else:
    ans = (k // 2) * (k // 2 + 1)

print((int(ans)))


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

k = int(input())
print((k // 2 * (k - k // 2)))


n = int(input())
odd = list()
even = list()

for i in range(n):
    if i % 2 == 0:
        even.append(i)
    elif i % 2 != 0:
        odd.append(i)

print(len(odd) * len(even))

N = int(input())
if N % 2 == 0:
  print(int((N/2)**2))
else:
  print((N//2)*(N//2 + 1))

k = int(input())
print((k//2) * (k - k//2))

import math

K = int(input())
print((math.ceil(K / 2) * math.floor(K / 2)))


K = int(input())

if K%2 == 1:
  print((K//2)*(K//2 + 1))
else:
  print((K//2)**2)

n=int(input())
if n%2==0:
  print(n**2//4)
else:
  print((n**2-1)//4)

k=int(input())
if k % 2 == 0:
  kazu = k//2
  print(kazu**2)
  
else:
  kazu = k //2
  print( kazu * (kazu+1))

K = int(input())
x = int(K/2)
if K%2 == 0:
  print((x*x))
else:
  print((x*(x+1)))