#include<stdio.h>

int xmin, xmax, ymin, ymax;
FILE *fh;
int nvertices;
int i;
int ncase;
int posx, posy;
int newx, newy;
int startx,starty;

int max(int x, int y)
{
  return x>y?x:y;
}

int min(int x,int y)
{
  return x<y?x:y;
}

void process(void)
  {
    int j;

 xmin = -0x80000000;
 ymin = -0x80000000;
 xmax =  0x7fffffff;
 ymax =  0x7fffffff;

 fscanf(fh,"%d", &startx);
 fscanf(fh,"%d", &starty);
 posx=startx;
 posy = starty;
 for (i=1; i<nvertices; i++)
   {
     fscanf(fh, "%d", &newx);
     fscanf(fh, "%d", &newy);
     /*     printf ("READ: %d %d\n",newx,newy);*/
     if (newy==posy)
       {
	 if (newx>posx)
	   {
	     ymax = min(ymax, posy);
	   }
	 else
	   {
	     ymin = max(ymin, posy);
	   }
       }
     else
       if (newy<posy)
	 { 
	   xmax = min(xmax, posx);
	 }
     else
       {
	 xmin = max(xmin, posx);
       }

     if (xmax<xmin || ymax<ymin) 
       {
	 printf("Floor #%d\nSurveillance is impossible.\n\n", ncase);
	 for(j=i+1;j<nvertices;j++){fscanf(fh,"%d%d",&newx,&newy);}
	 return;
       }
     posx = newx;
     posy = newy;
   }
 newx = startx;
 newy = starty;
     if (newy==posy)
       {
	 if (newx>posx)
	   {
	     ymax = min(ymax, posy);
	   }
	 else
	   {
	     ymin = max(ymin, posy);
	   }
       }
     else
       if (newy<posy)
	 { 
	   xmax = min(xmax, posx);
	 }
     else
       {
	 xmin = max(xmin, posx);
       }

     if (xmax<xmin || ymax<ymin) 
       {
	 printf("Floor #%d\nSurveillance is impossible.\n\n", ncase);
	 return;
       }
     printf("Floor #%d\nSurveillance is possible.\n\n", ncase);
 
 
}


int main()
{

 fh = fopen("video.in", "r");
 ncase = 0;
 for(;;)
   {
 ncase++;
 fscanf(fh,"%d", &nvertices);
 /* printf("NVERT: %d\n",nvertices);*/
 if (nvertices==0) return 0;
 process();
   }
 return 0;
}