mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    X = int(input())
    for M in range(62):
        N = X ^ M
        cnt = 0
        for i in range(62):
            cnt += N >> i & 1
        if cnt == M:
            if N <= 2 * 10 ** 18:
                print(N)
                exit()
    print(-1)


if __name__ == '__main__':
    main()