#include <stdio.h>
#include <math.h>

#define DEBUG
#define MAX 100

FILE *inp;
int buf[101][2];
int n, pNum = 1;
int in[ 101 ];
int cnt = 0;

int oneCase() 
{
  int i, a, b, c, d;
  fscanf( inp, "%d\n", &n ); 
  if ( !n ) return 0;            /* ANPASSEN !!!! */

  cnt = 0;
  /* SOLVING: */
 for ( i = 0; i < n ; i++) { 
  fscanf( inp, "%d %d/n", &buf[ i ][0] , &buf[ i][1] );
 
}
  buf[i][0]= buf[0][0];
 buf[i][1]= buf[0][1];

  if ( buf[0][0] ==  buf[1][0] )
    if ( buf[0][1] < buf[1][1] ) b = 0;
    else b = 2;
  else
  if ( buf[0][0] < buf[1][0] ) b = 1;
    else b = 3;

  if ( buf[1][0] ==  buf[2][0] )
    if ( buf[1][1] < buf[2][1] ) c = 0;
    else c = 2;
  else
  if ( buf[1][0] < buf[2][0] ) c = 1;
    else c = 3;

  if ( buf[2][0] ==  buf[3][0] )
    if ( buf[2][1] < buf[3][1] ) d = 0;
    else d = 2;
  else
  if ( buf[2][0] < buf[3][0] ) d = 1;
    else d = 3;

   printf("Floor #%d\n", pNum );
  for ( i = 4; i < n + 1; i++ )
    {
      a = b;
      b = c;
      c = d;
      if ( buf[i-1][0] ==  buf[i][0] )
	if ( buf[i-1][1] < buf[i][1] ) d = 0;
	else d = 2;
      else
	if ( buf[i-1][0] < buf[i][0] ) d = 1;
	else d = 3;
      
      if ( a == (b + 1) % 4 && b == (c + 1) % 4 && b == d){
	printf("Surveillance is impossible.\n");
        cnt = -1;
    }
    }
      if ( cnt ==  0)
	printf("Surveillance is possible.\n" );  
  return 1;
}

int main() {

  inp = fopen( "video.in", "r" );

  /* for ( i=0; i < MAX; i++ ) buf[0];
  */

  while( oneCase() ) 
  {
    printf("\n");
    pNum++;
  }

  fclose( inp );
  return 0;
}