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

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