debug.h

template < class c > struct rge { c b, e; };
template < class c > rge<c> range(c i, c j) { return rge<c>{i, j}; }
template < class c > auto dud(c* x) -> decltype(cerr << *x, 0);
template < class c > char dud(...);
struct debug {
    
    ~debug() {}
    template < class c> typename enable_if<sizeof dud<c>(0) != 1, debug&>::type operator<<(c i) { cerr << boolalpha << i; return * this; }
    template < class c> typename enable_if<sizeof dud<c>(0) == 1, debug&>::type operator<<(c i) { return * this << range(begin(i), end(i)); }
    template < class c, class b > debug & operator <<(pair < b, c > d) {
	    return * this << "(" << d.first << ", " << d.second << ")";
    }
    template<class a,class b,class c> debug & operator <<(tuple<a,b,c> t) {
	    return * this << "(" << get<0>(t) << ", " << get<1>(t) << ", " << get<2>(t) << ")";
    }
    template<class a,class b,class c,class d> debug & operator <<(tuple<a,b,c,d> t) {
	    return * this << "(" << get<0>(t) << ", " << get<1>(t) << ", " << get<2>(t) << ", " << get<3>(t) << ")";
    }
    template < class c > debug & operator <<(rge<c> d) {
        *this << "{";
        for (auto it = d.b; it != d.e; ++it)
            *this << ", " + 2 * (it == d.b) << *it;
        return * this << "}";
    }
    
};
#define deb(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
template<typename Head, typename... Tail>
void debug_out(const char *name,Head H) {
    debug() << name << " == " << H;
    cerr << ";\n===========================\n";
}
template<typename Head, typename... Tail>
void debug_out(const char* names, Head H, Tail... T) {
    const char* comma = strchr(names+1,',');
    cerr.write(names, comma - names) << " == ";
    debug() << H << "; \n";
    debug_out(comma+1,T...);
}
#define db(...) debug_out(#__VA_ARGS__, __VA_ARGS__)