#include<bits/stdc++.h>
using namespace std;
int main()
{int a;
cin>>a;
if(a>=30) printf("%.1f",a*1.0);
else if(a>=20) printf("%.1f",a*1.2);
	else if(a>=10) 
	printf("%.1f",a*1.5);
		else printf("%.1f",a*1.8);

	return 0;
}

/**************************************************************
	Problem: 1304
	User: sf751616
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/