import sys
def I(): return int(sys.stdin.readline())
def LI(): return list(map(int,sys.stdin.readline().split()))

N =I()
"""
judge = int(0)
for i in range(N):
    judge ^= (i+1)
"""
t = N+1
judge = int(0)
while t>1:
    if t%2==1:
        judge=1
        break
    t = t//2

if judge==0:
    ans = "X"
else:
    ans = "O"
print(ans)