#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    if(n<=150) printf("%.1f",n*0.4463);
    else if(n>=151&&n<=400) printf("%.1f",(150*0.4463)+(n-150)*0.4663);
    else printf("%.1f",(150*0.4463)+(400-150)*0.4663+(n-400)*0.5663);
}
/**************************************************************
	Problem: 1463
	User: wuweimo
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/