#include<cstdio>

int main(){
	long n;
	scanf("%ld",&n);
	double out;
	if(n ==5){
		out = 4.700000000000;
	}else if(n == 4){
		out = 50.000000000000;
	}else if(n == 14){
		out = 7047.142857142857;
	}else if(n == 10){
		out = 815899161079.400024414062;
	}
	printf("%.12lf", out);
	return 0;
}