#include<iostream>

#include<cmath>

#include<algorithm>

#include<cstdio>

#define ll long long

#define rep(i,a,b) for(int i=a;i<=b;i++)

using namespace std;

const int maxn=;

const double eps=1e-;

struct point{

    double x,y;

    point(){}

    point(double xx,double yy):x(xx),y(yy){}

};

struct line{

    point a;//起点

    point p;//起点到终点的向量

    double angle;

};

double dot(point a,point b){ return a.x*b.x+a.y*b.y;}

double det(point a,point b){ return a.x*b.y-a.y*b.x;}

point operator *(point A,double p){ return point(A.x*p,A.y*p);}

point operator +(point A,point B){return point(A.x+B.x,A.y+B.y);}

point operator -(point A,point B){return point(A.x-B.x,A.y-B.y);}

double getangle(point a){ return atan2(a.y,a.x);}

double getangle(line a){ return getangle(a.p);}

point llintersect(line A,line B)

{

    point C=A.a-B.a;

    double t=det(C,B.p)/det(B.p,A.p);

    return A.a+A.p*t;

}

point s[maxn]; line t[maxn],q[maxn]; int head,tail;

bool cmp(line a,line b){

    double A=getangle(a),B=getangle(b);

    point t=(b.a+b.p)-a.a;

    if(fabs(A-B)<eps) return det(a.p,t)>=0.0;

    return A<B;

}

bool onright(line P,line a,line b)

{

    point o=llintersect(a,b);

    point Q=o-P.a;

    return det(Q,P.p)>; //如果同一直线上不能相互看到，则>=0

}

bool halfplaneintersect(int N)

{

    s[N+]=s[];

    rep(i,,N) t[i].a=s[i],t[i].p=s[i+]-s[i];

    sort(t+,t+N+,cmp);

    int tot=;

    rep(i,,N-) {

        if(fabs(getangle(t[i])-getangle(t[i+]))>eps)

          t[++tot]=t[i];

    }

    t[++tot]=t[N]; head=tail=;

    rep(i,,tot){

        while(tail>head+&&onright(t[i],q[tail],q[tail-])) tail--;

        while(tail>head+&&onright(t[i],q[head+],q[head+])) head++;

        q[++tail]=t[i];

    }

    while(tail>head+&&onright(t[head+],q[tail],q[tail-])) tail--;return tail-head>;

}

void solve(int C,int N)

{

    for(int i=N;i>=;i--) scanf("%lf%lf",&s[i].x,&s[i].y);

    printf("Floor #%d\n",C);

    if(halfplaneintersect(N)) puts("Surveillance is possible.\n");

    else puts("Surveillance is impossible.\n");

}

int main()

{

    int N,C=;

    while(~scanf("%d",&N)&&N) solve(++C,N);

    return ;

}