#include <stdio.h>

struct point
{
	double x;
	double y;
};
#define MIN 1e-13

int main()
{
	int maxI,maxJ;
	int i,j,k;
	bool through;
	double maxLen=0;
	int max;
	double l,b,l0,b0;
	double x1,y1,x2,y2;
	point points[21];
	int n;
	double lenth,height;
	int past;
	while(1)
	{
		scanf("%d",&n);
		if(n==0)
			break;
		for(i=0; i<n; i++)
			scanf("%lf%lf",&points[i].x,&points[i].y);
		past=0;
		maxLen=0;
		max=0;
		through=false;
		for(i=0; i<n; i++)
		{
			for(j=0; j<n; j++)
			{
				if(i==j)
					continue;
				x1=points[i].x;
				y1=points[i].y;
				x2=points[j].x;
				y2=points[j].y-1;
				l=(y2-y1)/(x2-x1);			//y-y1=k(x-x1)
				b=-l*x1+y1;
//				printf("%f,%f\n",l,b);
				past=0;
				for(k=0 ;k<n; k++)
				{
					height=l*points[k].x+b;
					if(height>=points[k].y-1 && height<=points[k].y)
					{
						past=k+1;
					}
					else
						break;
				}
//				printf("%d\n",past);
				if(past==n)
				{
					through=true;
					break;
				}
				if(past==0)
					continue;
				l0=(points[past].y-points[past-1].y)/(points[past].x-points[past-1].x);
				b0=points[past].y-points[past].x*l0;
				
//				printf("%f,%f\n",l0,b0);
				if(l<l0)
					b0--;
				lenth=(b0-b)/(l-l0);
				if(lenth>maxLen)
				{
					maxLen=lenth;
					maxI=i;
					maxJ=j;
				}

				
			}//for j
			if(through==true)
				break;
		}//for i
		if(through==true)
			printf("Through all the pipe.\n");
		else
			printf("%.2f\n",maxLen);
//		printf("%d %d\n",maxI,maxJ);
	}//while
	return 0;

}