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

/**************************************************************
	Problem: 1304
	User: ljl2
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/