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

/**************************************************************
	Problem: 1304
	User: huangcanwu
	Language: C++
	Result: Accepted
	Time:28 ms
	Memory:2072 kb
****************************************************************/