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

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