def seisuwa(N):
    M = 0
    for n in range(1, N):
        M += n
    Nl = []
    for i in range(1, N + 1):
        if N % i == 0:
            Nl.append(i)
    for j in range(1, len(Nl) + 1):
        if M % Nl[-j] == 0:
            ans = Nl[-j]
            break
    return ans

def main():
    N = int(input())
    print(seisuwa(N))

if __name__ == '__main__':
    main()