#include <cmath>
#include <cstdlib>
#include <set>
#include <utility>
#include <iostream>

using namespace std;

class test {
	pair<int,int> pos;
public:
	test(int x,int y):pos(x,y){}
	friend bool operator==(const test & t1,const test & t2) {
		return abs(t1.pos.first - t2.pos.first) <= 8 &&
				abs(t1.pos.second - t2.pos.second) <= 8;
	}
	friend bool operator<(const test & t1,const test & t2) {
		if(t1 == t2) return false;
		else if(abs(t1.pos.first - t2.pos.first) <= 8) return t1.pos.second < t2.pos.second;
		else if(abs(t1.pos.second - t2.pos.second) <= 8) return t1.pos.first < t2.pos.first;
		else //if(!(abs(t1.pos.x - t2.pos.x) < 8) && !(abs(t1.pos.y - t2.pos.y) < 8))
			return t1.pos.first < t2.pos.first;
	}
	void print() const {
		cout<<pos.first<<" "<<pos.second<<endl;
	}
};

int main()
{
	multiset<test> ms;
	ms.insert(test(50,117));
	ms.insert(test(62,129));
	ms.insert(test(54,142));
	if(ms.end() == ms.find(test(51,142))) cout<<"error"<<endl;
	return EXIT_SUCCESS;
}