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