#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);
}
/**************************************************************
	Problem: 1304
	User: huanglingkai
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/