#include <bits/stdc++.h>
using namespace std;
int main(){
	double a;
	cin>>a;
	if(a>20)a=a*1.98;
	else a=a*1.68;
	printf("%.2f",a);
	return 0;
	}
/**************************************************************
	Problem: 1643
	User: ljl2
	Language: C++
	Result: Accepted
	Time:12 ms
	Memory:2072 kb
****************************************************************/