#include<stdio.h>

int main()

{

    double x,a;

    scanf("%lf",&x);

    if(x<=150)

    {

        a=x*0.4463;

        printf("%.1lf",a);

    }
     else if(x>=151&&x<=400)

    {

        a=150*0.4463+(x-150)*0.4663;

        printf("%.llf",a);

    }

     else if

    {

        a=150*0.4463+(400-150)*0.4663+(x-400)*0.5663;

        printf("%.1lf",a);

    }


}