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



	return 0;
}


/**************************************************************
	Problem: 1304
	User: 21A
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/