> #include <stdio.h>
> #include <math.h>
> 
> #define precision 0.000000001
> typedef struct
> {
> 	double x,y;
> }point;
> 
> point p[22],q[22];
> double max;
> int mark,n;
> 
> int dblcmp(double d)
> {
> 	if(fabs(d)<precision)
> 		return 0;
> 	return (d>0)?1:-1;
> }
> double det(double x1,double y1,double x2,double y2)
> {
> 	return x1*y2-x2*y1;
> }
> double cross(point a,point b,point c)
> {
> 	return det(b.x-a.x,b.y-a.y,c.x-a.x,c.y-a.y);
> }
> int segcross(point a,point b,point c,point d)
> {
> 	if(dblcmp(cross(a,b,c))*dblcmp(cross(a,b,d))<0)
> 		return 1;
> 	if(dblcmp(cross(a,b,c))*dblcmp(cross(a,b,d))==0)
> 		return 2;
> 	return 0;
> }
> double point_X(point a,point b,point c,point d)
> {
> 	double e=d.x-c.x,f=b.x-a.x,g=d.y-c.y,k=b.y-a.y,l,m;
> 	l=e*k;
> 	m=f*g;
> 	return (e*f*(c.y-a.y)+l*a.x-m*c.x)/(l-m);
> }
> int judge(int a,int b)
> {
> 	int i,flag,temp;
> 	double c;
> 	for(i=0;i<n;i++)
> 	{
> 		if(segcross(p[a],q[b],p[i],q[i]))
> 			flag=i;
> 		else
> 			break;
> 	}
> 	if(mark==n-1)
> 		return 1;
> 	if(mark<=flag)
> 	{
> 		mark=flag;
> 		temp=segcross(p[a],q[b],p[mark],p[mark+1]);
> 		if(temp==1||(temp==2&&segcross(p[a],q[b],q[mark],q[mark+1])==0))
> 			c=point_X(p[a],q[b],p[mark],p[mark+1]);
> 		else
> 			c=point_X(p[a],q[b],q[mark],q[mark+1]);
> 		if(c>max)
> 			max=c;
> 	}
> 	return 0;
> }
> 
> int main()
> {
> 	int i,j;
> 	while(scanf("%d",&n)&&n)
> 	{
> 		for(i=0,mark=0,max=-10e30;i<n;i++)
> 		{
> 			scanf("%lf%lf",&p[i].x,&p[i].y);
> 			q[i].x=p[i].x;
> 			q[i].y=p[i].y-1;
> 		}
> 		for(i=0;i<n;i++)
> 		{
> 			for(j=0;j<n;j++)
> 				if(i!=j)
> 					if(judge(i,j))
> 						break;
> 			if(j!=n)
> 				break;
> 		}
> 		if(i==n)
> 			printf("%.2lf\n",max);
> 		else
> 			printf("Through all the pipe.\n");
> 	}
> 	return 0;
> }