"""
# 式変形すべきかもしれないが実験した方が速いか
from math import gcd
for N in range(2, 100):
    S = []
    for start in range(1, 100):
        s = sum(range(start, start+N))
        S.append(s)
    g = gcd(*S)
    print('N', N, 'g', g)
"""

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