#include <stdio.h>

int status;
int array[200][2];
int max;
int iter;
int res;
int lefts, ups, downs, rights;

int left(int);
int up(int);
int right(int);
int down(int);

int main() 
{
  FILE *in = fopen("video.in","r");

  for(iter = 1; ; iter++)
    {
      int i;
      
      for(i = 0; i < 200; i++)
	array[i][0] = array[i][1] = 0;
      lefts = ups = downs = rights =0;

      fscanf(in, "%d", &max);
      if (max == 0)
	break;
      
      status = 0;
      for(i = 0; i < max; i++)
	{
	  fscanf(in, "%d", &array[i][0]);
	  fscanf(in, "%d", &array[i][1]);
	}

      if(array[0][0] == array[1][0] && array[0][1] < array[1][1])
	res = left(0);
      else if(array[0][0] == array[1][0] && array[0][1] > array[1][1])
	res = right(0);
      else if(array[0][0] < array[1][0] && array[0][1] == array[1][1])
	res = up(0);
      else if(array[0][0] > array[1][0] && array[0][1] == array[1][1])
	res = down(0);

      if((res +1 == max) && (lefts <= rights) && (ups <= downs))
	printf("Floor #%d\nSurveillance is possible.\n\n", iter);
      else
	printf("Floor #%d\nSurveillance is impossible.\n\n", iter);
    }

  fclose(in);
  return(0);
}

int left(int akt)
{
  int h = 0;

  if(status > 4) 
    return akt;
  status++;

  if(akt < max)
    {
      while(akt+1 < max 
	    && (array[akt][0] == array[akt+1][0] 
		|| array[akt][1] < array[akt+1][1]
		)
	    )
	{
	  if(array[akt][1] < array[akt+1][1])
	    ups += array[akt+1][1] - array[akt][1];
	  akt++;
	}
      
      
      return(up(akt));
    }
  else return 0;
}

int up(int akt)
{
  int h = 0;

  if(status > 4) 
    return akt;
  status++;

  if(akt < max)
    {
      while(akt+1 < max 
	    && (array[akt][0] < array[akt+1][0] 
		|| array[akt][1] == array[akt+1][1]
		)
	    )
	{

	  if(array[akt][0] < array[akt+1][0])
	    rights += array[akt+1][0] - array[akt][0];
	  akt++;
	}
      
      return(right(akt));
    }
  else return 0;
}

int right(int akt)
{
  int h = 0;

  if(status > 4) 
    return akt;
  status++;

  if(akt < max)
    {
      while(akt+1 < max 
	    && (array[akt][0] == array[akt+1][0] 
		|| array[akt][1] > array[akt+1][1]
		)
	    )
	{
	  if(array[akt][1] > array[akt+1][1])
	    downs += array[akt][1] - array[akt+1][1];
	  akt++;
	}
      
      return(down(akt));
    }
  else return 0;
}

int down(int akt)
{
  int h = 0;

  if(status > 4) 
    return akt;
  status++;

  if(akt < max)
    {
      while(akt+1 < max 
	    && (array[akt][0] > array[akt+1][0] 
		|| array[akt][1] == array[akt+1][1]
		)
	    )
	{
	  if(array[akt][0] > array[akt+1][0])
	    lefts += array[akt][0] - array[akt+1][0];
	  akt++;
	}
      
      return(left(akt));
    }
  else return 0;
}