#include<iostream>
#include<cstdio>
using namespace std;
int main(){
	double a;
	double b,c;
	cin>>a;
	if(a<=150)
	b=a*0.4463;
	if(a>150&&a<=400)
	b=150*0.4463+(a-150)*0.4663;
	if(a>=401){
	 
	b=150*0.4463+249*0.4663+(a-401)*0.5663+0.5663;}
	printf("%.1f",b);
	return 0;
}