#include <bits/stdc++.h>
using namespace std;
int main(){
int a;
float b;
	cin>>a;
	if(a>=30){
b=a*1.0;
	} else if(a>=20&&a<=29){
b=a*1.2;
	}else if(a>=10&&a<=19){
b=a*1.5;
	}else{
	b=a*1.8;
	}
	printf("%.1f",b);
	return 0;
	}

/**************************************************************
	Problem: 1304
	User: mc002
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/