p4.cpp

好东西,绝对是好东西,我向大家推荐

#include <iostream.h>
#include <stdio.h>
int main()
{
	double x,y;
	while(cin>>x)
	{
		if(x==2) {y=x;}
			else {y=1.0/(x-2.0);}
		printf("%.4f\n",y);
	}
}