n = int(input())
l = [1 << i for i in range(60) if 1 << i & n]
ans = []
for b in range(1, 1 << len(l)):
    cnt = 0
    for i in range(len(l)):
        if 1 << i & b:
            cnt += l[i]
    ans.append(cnt)
print(sorted(ans)[(len(ans) + 1) // 2 - 1])