#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <tuple>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;
class InsidePoints { public:
vector <int> construct(vector <int> x, vector <int> y)
{
map<int, set<int>> x2y;
for (int i = 0; i < x.size(); ++i)
x2y[x[i]].insert(y[i]);
vector<pair<int,int>> left;
vector<pair<int, int>> upper;
vector<pair<int, int>> lower;
vector<pair<int, int>> right;
int prevx = -99999999;
int prevy = -99999999;
for (auto it : x2y) {
int x = it.first;
set<int> ys = it.second;
if (prevx == -99999999) {
upper.emplace_back(x, *ys.rbegin() + 1);
lower.emplace_back(x, *ys.begin() - 1);
for (int yy = *ys.rbegin(); yy >= *ys.begin(); --yy)
left.emplace_back(ys.count(yy) ? x - 1 : x, yy);
}
else {
for (int xt = prevx + 1; xt < x; ++xt) {
upper.emplace_back(xt, prevy+1);
lower.emplace_back(xt, prevy);
}
upper.emplace_back(x, *ys.rbegin() + 1);
int id = -1;
for (int yy = *ys.rbegin(); yy >= *ys.begin(); --yy)
if (ys.count(yy) == 0) {
lower.emplace_back(x, yy);
lower.emplace_back(x-1, id--);
}
lower.emplace_back(x, *ys.begin() - 1);
}
if (x2y.rbegin()->first == x) {
for (int yy = *ys.rbegin(); yy >= *ys.begin(); --yy)
right.emplace_back(ys.count(yy) ? x + 1 : x, yy);
}
prevx = x;
prevy = *ys.rbegin();
}
vector<pair<int,int>> ans;
ans.insert(ans.end(), left.begin(), left.end());
ans.insert(ans.end(), lower.begin(), lower.end());
ans.insert(ans.end(), right.rbegin(), right.rend());
ans.insert(ans.end(), upper.rbegin(), upper.rend());
vector<int> flat_ans;
for (auto xy : ans) {
flat_ans.push_back(xy.first);
flat_ans.push_back(xy.second);
}
return flat_ans;
}
};
// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
{ ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
{ os << "{ ";
for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const vector <int>& Expected, const vector <int>& Received) {
bool ok = (Expected == Received);
if(ok) cerr << "PASSED" << timer() << endl; else { cerr << "FAILED" << timer() << endl;
cerr << "\to: " << Expected << endl << "\tx: " << Received << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END verify_case(_, InsidePoints().construct(x, y));}
int main(){
CASE(0)
int x_[] = {4};
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = {7};
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = {3, 7, 4, 8, 5, 6 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(1)
int x_[] = {4, 6};
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = {7, 7};
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = {3, 6, 7, 6, 7, 8, 5, 7, 3, 8 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(2)
int x_[] = {1, 1, 2, 2};
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = {1, 2, 1, 2};
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = {0, 0, 3, 0, 3, 3, 0, 3 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(3)
int x_[] = {1, 2, 3, 3, 3, 3, 5, 4};
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = {3, 3, 1, 5, 2, 4, 3, 3};
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = {0, 2, 2, 2, 2, 0, 4, 0, 4, 2, 6, 2, 6, 4, 4, 4, 4, 6, 2, 6, 2, 4, 3, 3, 1, 4, 0, 4 };
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
/*
CASE(4)
int x_[] = ;
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = ;
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = ;
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
CASE(5)
int x_[] = ;
vector <int> x(x_, x_+sizeof(x_)/sizeof(*x_));
int y_[] = ;
vector <int> y(y_, y_+sizeof(y_)/sizeof(*y_));
int __[] = ;
vector <int> _(__, __+sizeof(__)/sizeof(*__));
END
*/
}
// END CUT HERE