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

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