const int Max_N = 1010 ;
double add(double a, double b){
    if( fabs(a + b) < EPS * ( fabs(a) + fabs (b)) ) return 0 ;
    return a + b ;
}
struct Point{
    double x, y ;
    Point(){}
    Point(double x , double y):x(x),y(y){}
    Point operator +( Point p){
        return Point(add(x , p. x) , add(y , p.y) ) ;
    }
    Point operator -( Point p){
        return Point(add(x ,- p. x) , add(y ,- p.y) ) ;
    }
    Point operator * (double d){
        return Point( x*d , y * d ) ;
    }
    double operator * (Point p){
        return add(x * p.x , y * p.y) ;
    }
    double operator ^(Point p){
        return add(x * p.y , -y*p.x) ;
    }
}po[Max_N];
//判断点p是否在线段p1p2内
int on_segment(Point p1, Point p2, Point p){
    if( ((p1 - p).x * (p2 - p).x <= 0) &&   ((p1 - p).y * (p2 - p).y <= 0))
        return 1;
    return 0;
}
struct Line{
    Point st, ed;
    Line(){}
    Line(Point a, Point b){
    st = a ;
    ed = b ;
    }
}line[Max_N *2];
//判断线段p1p2与q1q2 是否相交
int intersection(Line l1, Line l2 ){
    Point p1 , p2 ,q1, q2 ;
    p1 = l1.st ;
    p2 = l1.ed ;
    q1 = l2.st ;
    q2 = l2.ed ;
    double d1, d2, d3, d4;
    d1 = (p2 - p1)^(q1 - p1) ;
    d2 = (p2 - p1)^(q2 - p1) ;
    d3 = (q2 - q1)^(p1 - q1) ;
    d4 = (q2 - q1)^(p2 - q1) ;
    if((d1 == 0 && on_segment(p1, p2, q1))
    || (d2 == 0 && on_segment(p1, p2, q2))
    || (d3 == 0 && on_segment(q1, q2, p1))
    || (d4 == 0 && on_segment(q1 ,q2 ,p2)))
        return 1;
    else if(d1 * d2 < 0 && d3 * d4 < 0)
        return 1;
    return 0;
}
int  n;
bool judge(){
    int i , j ;
    for(i = 0 ;  i < n ; i++)
        for(j = i + 2; j <= n+ i - 2 ; j++)
            if( intersection( line[i] , line[j]) )
                return 0 ;
    return 1;
}
int main(){
    int  i , j , k =1;
    while(scanf("%d" , &n) && n){
        double area = 0.0 ;
        for(i = 0 ; i < n ; i++)
            scanf("%lf%lf", &po[i].x , &po[i].y) ;
        for(i =0 ;i < n ; i++){
            line[i].st = po[i];
            line[i].ed = po[(i+1) % n ] ;
        }
        for(i = 0 ; i< n ; i++)   // 把线段扩展一倍时，特别好处理， 与线段不相邻的其他线段
            line[n + i] = line[i] ;
        if( k != 1) puts("") ;
        printf("Figure %d: ", k++) ;
         if(n < 3)
        {
            printf("Impossible\n") ;
            continue ;
        }
        if(judge()){
            for(i = 0 ;i < n ; i++)
            area += po[i]^po[ (i+1) % n ] ;
        area = area < 0 ? -area : area ;
        printf("%.2lf\n" , area / 2.0 ) ;
        }
        else{
            printf("Impossible\n") ;
        }
    }
    return 0;
}