#include<bits/stdc++.h>
using namespace std;

int main(){
	int n;
	float a;
	cin>>n;
	if(n<10){
		a=n*1.8;
		printf("%.1f",a);
	}
	if(n>=10&&n<=19){
		a=n*1.5;
		printf("%.1f",a);
	}
	if(n>=20&&n<=29){
		a=n*1.2;
		printf("%.1f",a);
	}
	if(n<=30){
		a=n*1;
		printf("%.1f",a);
	}
		
	
}

/**************************************************************
	Problem: 1304
	User: linzihang
	Language: C++
	Result: Wrong Answer
****************************************************************/