#include<bits/stdc++.h>
using namespace std;
int main(){
    double n,y;
    cin>>n;
    if(n<=150){
    	y=n*0.4463;
    } 
    if(n>150&&n<=400){
    	y=150*0.4463+(n-150)*0.4663;
    } 
    if(n>400){
    	 y=150*0.4463+250*0.4663+(n-400)*0.5663;
    }
    printf("%.1f",y);
}
/**************************************************************
	Problem: 1463
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/