// combat
#include <fstream>
#include <iostream>
using namespace std;

int n,m;
double point[1000][2];
double ans[40000][2];
int cnt;

double check(int p1,int p2,int p3)
{
  double ax = ans[p1][0];
  double ay = ans[p1][1];
  double bx = point[p2][0];
  double by = point[p2][1];
  double cx = point[p3][0];
  double cy = point[p3][1];
  return (ax*by + bx*cy + cx*ay - (ax*cy + bx*ay + cx*by));
}

int solve(int sets)
{
  cnt = 0;
  bool flag_p,flag_m;
  for(int i=0;i<m;i++){
    flag_p = false;
    flag_m = false;
    for(int j=0;j<n;j++){
      double a = check(i,j,(j+1)%n);
      if(a > 0.00001){
        flag_p = true;
      }else if(a < -0.0001){
        flag_m = true;
      }
    }
    
    if(flag_p && flag_m){
    }else{
      cnt++;
    }
  }
  
  cout << "Floor #" << sets << endl;
  cout << "Surveillance is ";
  if(cnt){
    cout << "possible.";
  }else{
    cout << "impossible.";
  }
  cout << endl << endl;
}

int main()
{
  ifstream cin("video.txt");
  
  for(int sets=1;;sets++){
    cin>>n;

    if(!n ) break;
    for(int i=0;i<n;i++){
      cin>>point[i][0]>>point[i][1];
    }

    m=0;
    for (int i=0;i<n;i++){
      for (int j=0;j<n;j++){
        ans[m][0]=(point[i][0]+point[j][0])/2;
        ans[m][1]=(point[i][1]+point[j][1])/2;
        m++;
      }
    }
    solve(sets);
  }
  
  return 0;
}