#include<iostream>
using namespace std;
int main()
{
    double a,b;
    cin>>a;
    if(a<150)
        b=a*0.4463;
    if(151<=a&&a<=400)
        b=150*0.4463+(a-150)*0.4663;
    if(a>400)
        b=150*0.4463+250*0.4663+(a-400)*0.5663;
    printf("%.1f",b);
    return 0;
}