#include<bits/stdc++.h> using namespace std; int main() { double x; cin>>x; double cost; if(x<=20) { cost=x1.68; } else { cost=x1.98; } cout<<fixed<<setprecision(2)<<cost; return 0; }

#include<bits/stdc++.h>
using namespace std;
int main()
{
	double x;
	cin>>x;
	double cost;
	if(x<=20)
	{
		cost=x*1.68;
	}
	else
	{
		cost=x*1.98;
	}
	cout<<fixed<<setprecision(2)<<cost;
	return 0;
}