#include <stdio.h>
int main()
{
    int d;
    double s=0;
    scanf("%d",&d);
    if(d<=150)
    s=d*0.4463;
    else if(d>150&&d<=400)
    s=150*0.4463+(d-150)*0.4663;
    else
    s=150*04463+250*0.4663+(d-400)*0.5563;
    printf("%.1f",s);
    return 0;
}