#include <fstream>
#include <iostream>
#include <vector>
#include <climits>
#include <cassert>

using namespace std;

#define cin fin

class Point {
public:
	int x, y;
};

vector<Point> P;

bool compute() {
	int xmax = INT_MAX;
	int xmin = INT_MIN;
	int ymax = INT_MAX;
	int ymin = INT_MIN;

	for ( int i = 0; i < P.size(); i++ ) {
		const int x1 = P[i].x;
		const int y1 = P[i].y;
		const int x2 = P[(i+1)%P.size()].x;
		const int y2 = P[(i+1)%P.size()].y;

		if ( x1 == x2 && y1 > y2 )
			xmax = min(xmax, x1);
		else if ( x1 == x2 && y1 < y2 )
			xmin = max(xmin, x1);
		else if ( y1 == y2 && x1 < x2 )
			ymax = min(ymax, y1);
		else if ( y1 == y2 && x1 > x2 )
			ymin = max(ymin, y1);
		else
			assert( false );
	}

	if ( xmin <= xmax && ymin <= ymax ) return true;
	return false;
}

int main() {
	ifstream fin("video.txt");

	for ( int n = 1; true; n++ ) {
		int npoint; cin >> npoint;
		if ( npoint == 0 ) break;

		P.resize(npoint);
		for ( int i = 0; i < npoint; i++ )
			cin >> P[i].x >> P[i].y;

		cout << "Floor #" << n << endl;
		if  (compute() )
			cout << "Surveillance is possible." << endl;
		else
			cout << "Surveillance is impossible." << endl;
		cout << endl;
	}

	return 0;
}