# include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float a;
	cin>>n;
	if(n>=30){
		a=1.0*n;
		cout<<fixed<<setprecision(1)<<a;
	}
	if(n>19&&n<20){
		a=1.2*n;
		cout<<fixed<<setprecision(1)<<a;
	}
	if(n>10){
		a=1.5*n;
		cout<<fixed<<setprecision(1)<<a;
	}cout<<fixed<<setprecision(1)<<a;


/**************************************************************
	Problem: 1304
	User: caiqiaoxi
	Language: C++
	Result: Compile Error
****************************************************************/