#include<bits/stdc++.h>
using namespace std;
double n=0.0;
int a;
int main()
{
	cin>>a;
	if(a<=150)
    {
        n+=a*0.4463;
		printf("%.1f", n);
	}
    else if(a>150&&a<=400)
    {
		n+=150.0*0.4463+(a-150)*0.4663;
	}
    else
    {
		n+=150.0*0.4463+250*0.4663+(a-400)*0.5663;
	}
	printf("%.1f", n);
	return 0;
}