#include <string>
#include <iosfwd> // for istream, ostream
 
namespace std {
    template <size_t N> class bitset;
 
    // bitset operators:
    template <size_t N>
        bitset<N> operator&(const bitset<N>&, const bitset<N>&) noexcept;
    template <size_t N>
        bitset<N> operator|(const bitset<N>&, const bitset<N>&) noexcept;
    template <size_t N>
        bitset<N> operator^(const bitset<N>&, const bitset<N>&) noexcept;
    template <class charT, class traits, size_t N>
        basic_istream<charT, traits>&
        operator>>(basic_istream<charT, traits>& is, bitset<N>& x);
    template <class charT, class traits, size_t N>
        basic_ostream<charT, traits>&
        operator<<(basic_ostream<charT, traits>& os, const bitset<N>& x);
 
    // Hash support
    template <class T> struct hash;
    template <size_t N> struct hash<bitset<N> >;
 
}

template<size_t N> class bitset {
public:
    // bit reference:
    class reference {
        friend class bitset;
        reference() noexcept;
    public:
        ~reference() noexcept;
        reference& operator=(bool x) noexcept;          //  for b[i] = x;
        reference& operator=(const reference&) noexcept;//  for b[i] = b[j];
        bool operator~() const noexcept;                //  flips the bit
        operator bool() const noexcept;                 //  for x = b[i];
        reference& flip() noexcept;                     //  for b[i].flip();
 
    };
 
    //constructors:
    constexpr bitset() noexcept;
    constexpr bitset(unsigned long long val) noexcept;
    template<class charT, class traits, class Allocator>
        explicit bitset(
            const basic_string<charT,traits,Allocator>& str,
            typename basic_string<charT,traits,Allocator>::size_type pos = 0,
            typename basic_string<charT,traits,Allocator>::size_type n =
                basic_string<charT,traits,Allocator>::npos,
            charT zero = charT('0'), charT one = charT('1'));
    template <class charT>
        explicit bitset(
            const charT* str,
            typename basic_string<charT>::size_type n = basic_string<charT>::npos,
            charT zero = charT('0'), charT one = charT('1'));
 
    // bitset operations:
    bitset<N>& operator&=(const bitset<N>& rhs) noexcept;
    bitset<N>& operator|=(const bitset<N>& rhs) noexcept;
    bitset<N>& operator^=(const bitset<N>& rhs) noexcept;
    bitset<N>& operator<<=(size_t pos) noexcept;
    bitset<N>& operator>>=(size_t pos) noexcept;
    bitset<N>& set() noexcept;
    bitset<N>& set(size_t pos, bool val = true);
    bitset<N>& reset() noexcept;
    bitset<N>& reset(size_t pos);
    bitset<N> operator~() const noexcept;
    bitset<N>& flip() noexcept;
    bitset<N>& flip(size_t pos);
 
    // element access:
    constexpr bool operator[](size_t pos) const; // for b[i];
    reference operator[](size_t pos); // for b[i];
 
 
    unsigned long to_ulong() const;
    unsigned long long to_ullong() const;
    template <class charT = char,
            class traits = char_traits<charT>,
            class Allocator = allocator<charT> >
        basic_string<charT, traits, Allocator>
        to_string(charT zero = charT('0'), charT one = charT('1')) const;
 
    size_t count() const noexcept;
    constexpr size_t size() noexcept;
 
    bool operator==(const bitset<N>& rhs) const noexcept;
    bool operator!=(const bitset<N>& rhs) const noexcept;
 
    bool test(size_t pos) const;
    bool all() const noexcept;
    bool any() const noexcept;
    bool none() const noexcept;
 
    bitset<N> operator<<(size_t pos) const noexcept;
    bitset<N> operator>>(size_t pos) const noexcept;
};