def solve():
    import math
    N = int(input())
    if N < 2:
        print(0)
    elif N%2==0:
        print(N-1)
    else:
        x = 2**int(math.log2(N)) - 1
        if x < N/2:
            print(0)
        else:
            print(x*2-N+1)


if __name__ == "__main__":
    solve()