#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	float k;
	cin>>a;
	if(a>=30){
		k=a;
	}
	if(a<=29&&a>=20){
		k=a*1.2;
	}
	if(a>=10&&a<=19){
		k=a*1.5;
	}
	if(a<=10){
		k=a*1.8;
	}
	printf("%.1f",k);
}
/**************************************************************
	Problem: 1304
	User: tonghuawei
	Language: C++
	Result: Accepted
	Time:19 ms
	Memory:2072 kb
****************************************************************/