#include<bits/stdc++.h>
using namespace std;
int main()
{   double h,w=0;scanf("%lf",&h);
    if(h<=150.0)w=h*0.4463;
    else if(h>=151&&h<=400)
    w=150*0.4463+(h-150)*0.4663;
    else w=150*0.4463+250*0.4663+(w-400)*0.5663;
    printf("%.1f",w);
    return 0;
}