#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("infasuratoare.in");
ofstream g("infasuratoare.out");
struct ura
{
	double x, y;
}v[120002];
int arie (int xa,int xb,int xc,int ya,int yb,int yc)
{
	if ((xa*yb+xb*yc+xc*ya-xc*ya-xa*yc-xb*ya)>=0)
		return 1;
	else return 0;
}
bool cmp (ura a, ura b)
{
	if (a.x>b.x)
		return false;
	else {
		if (a.x<b.x)
		return true;
	    else
		{
			if (a.y<b.y)
				return true;
			else return false;
		}
	}

}
int main()
{

    int n;
    f>>n;
    for (int i=1; i<=n;i++)
		f>>v[i].x>>v[i].y;
	sort (v+1,v+n+1, cmp);
	for (int i=1; i<=n; i++)
       g<<v[i].x<<v[i].y;
	return 0;
}