#include<bits/stdc++.h>
using namespace std;
int a;
float sum=0;
int main(){
   cin>>a;
if(a<=150)
{
sum*=0.4463;
}
else if(a>=151&&a<=400)
{
sum+=150*0.4463;
sum+=(a-150)*0.4663;
}
if(a>=401)
{
sum+=150*0.4463;
sum+=(400-150)*0.4663;
sum+=(a-400)*0.5663;
}
printf("%.1lf\n",sum);
    return 0;
}