#include<bits/stdc++.h>
using namespace std;
int main()
{
	int a;
	double s;
	cin>>a;
	
	if(a>=30){
    	s=a*1.0;
	}else if(a>=20){
    	s=a*1.2;
	}else if(a>=10){
    	s=a*1.5;
	}else{
    	s=a*1.8;
	}
	
	printf("%.1f",s);
	
	
	
	
	return 0;
}

/**************************************************************
	Problem: 1304
	User: czr
	Language: C++
	Result: Accepted
	Time:27 ms
	Memory:2072 kb
****************************************************************/