cf022D.cc

#include <iostream>
#include <algorithm>
#include <utility>
#include <vector>
using namespace std;

int main() {
	typedef pair<int,int> ii;
	int N;
	cin >> N;
	vector<ii> S(N);

	for( auto &s : S ) {
		cin >> s.second >> s.first;
		if( s.first < s.second ) swap(s.first,s.second);
	}

	sort(S.begin(),S.end());

	for( int i = 0 ; i < N ; ++i ) swap(S[i].first,S[i].second);

	vector<int> sol;


	vector<bool> used(N,false);

	for( int i = 0 ; i < N ; ++i ) {
		if( used[i] ) continue;
		sol.push_back(S[i].second);
		for( int j = i ; j < N ; ++j ) {
			if( S[j].first <= S[i].second ) used[j] = true;
		}
	}

	cout << sol.size() << endl;
	for( auto s : sol ) {
		cout << s << " ";
	}
	cout << endl;
	return 0;
}