import fractions



N = int(eval(input()))

print((int(N * 2 / fractions.gcd(N, 2))))

import fractions



N = int(eval(input()))



print((N*2//fractions.gcd(2, N)))

import fractions

N = int(eval(input()))
print((int(N * 2 / fractions.gcd(N, 2))))

import fractions

N = int(eval(input()))
print((N * 2 // fractions.gcd(2, N)))

-print((int(N * 2 / fractions.gcd(N, 2)))) +print((N * 2 // fractions.gcd(2, N)))