#include<bits/stdc++.h>
using namespace std;
int main(){
    double e,money=0;
    cin>>e;
    if(e<=150)	
        money=e*0.4463;
    if(e>150||e==400)	
        money=150*0.4463+(e-150)*0.4663;
    if(e>400)		
        money=150*0.4463+250*0.4663+(e-400)*0.5663;
    printf("%.1lf\n",money);
    return 0;
}