#include<bits/stdc++.h>
using namespace std;
int main(){
	int g;
	float q;
	cin>>g;
	if(g>=30){
		q=g;
	}else if(g>=20&&g<=29){
		q=g*1.2;
	}else if(g>=10&&g<=19){
		q=g*1.5;
	}else{
		q=g*1.8;
	} 
	printf("%.1f",q);
	return 0;
}

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