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

#include <bits/stdc++.h>
using namespace std;
int main( )

{

int n;
double sum;
cin>>n;
if (n<=150)
{
sum=0.4463*n;
}
else if (n<=400 && n>=151)
{
sum=0.4463*150+0.4663*(n-150);
}
else if (n>=401)
{
sum=0.4463*150+0.4663*250+0.5663*(n-400);
}
cout<<fixed<<setprecision(1)<<sum;
return 0;

}