#include<bits/stdc++.h>
using namespace std;
int main()
{
    int x=0;
    double ans=0;
    cin>>x;
    if(x<=150) ans+=x*0.4463;
    else if(x>=151&&x<=400) {
        ans+=150*0.4463;
        ans+=(x-150)*0.4663;
    }
    else { 
        ans+=150*0.4463;
        ans+=(400-150)*0.4663;
        ans+=(x-400)*0.5663;
    }
    ans=int((ans*10)+0.5)/10.0;
    return 0;
}
//蒟蒻求助，各位大佬帮帮忙谢谢QwQ
//改了好几遍全pass了嘤嘤嘤