#include<bits/stdc++.h>
using namespace std;
int main()
{
int a;
float result;
cin>>a;
if(a>=30){
	result=a*1;
}
else if(a>=20&&a<=29){
	result=a*1.2;
}
else if(a>=10&&a<=19){
	result=a*1.5;
}else{
	result=a*1.8;
}

printf("%.1f",result);

	return 0;
}

/**************************************************************
	Problem: 1304
	User: hbq
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/