import math

def seisuwa(N):
    M = (N / 2) * (N - 1)
    M = int(M)
    Nl = []
    for i in range(1, int(math.sqrt(N)) + 1):
        if N % i == 0:
            Nl.append(i)
            Nl.append(N // i)
    Nl = sorted(Nl)
    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()