#include<bits/stdc++.h>
using namespace std;
int main (){
	int y;
	double j;
	cin>>y;
	if(y<=150){
		j=0.4463*y;
	}
	if(y>151&&y<=400){
		j=150*0.4463+(y-150)*0.4663;
	}
	else{
		j=150*0.4463+(400-150)*0.4663+(y-400)*0.5663;
	}
	printf("%.1lf\n",j);
	return 0;
}