#include using i32 = std::int32_t; using u32 = std::uint32_t; using i64 = std::int64_t; using u64 = std::uint64_t; using i128 = __int128_t; using u128 = __uint128_t; using isize = std::ptrdiff_t; using usize = std::size_t; class rep { struct Iter { usize itr; constexpr Iter(const usize pos) noexcept: itr(pos) { } constexpr void operator ++ () noexcept { ++itr; } constexpr bool operator != (const Iter& other) const noexcept { return itr != other.itr; } constexpr usize operator * () const noexcept { return itr; } }; const Iter first, last; public: explicit constexpr rep(const usize first, const usize last) noexcept: first(first), last(std::max(first, last)) { } constexpr Iter begin() const noexcept { return first; } constexpr Iter end() const noexcept { return last; } }; constexpr u64 popcount(const u64 x) { return __builtin_popcountll(x); } template using Vec = std::vector; void F_main() { u64 X; std::cin >> X; // N xor popcount(N) = X // N < 2^63, so popcount(N) <= 63 for (const auto ppc: rep(1, 64)) { const auto N = X ^ ppc; if (popcount(N) == ppc) { std::cout << N << '\n'; return; } } std::cout << -1 << '\n'; return; } int main() { std::ios_base::sync_with_stdio(false); #ifndef LOCAL std::cin.tie(nullptr); #endif F_main(); return 0; }