#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float q;
	cin>>n;
	if(n<10){
		q=n*2.2;
		cout<<q;
	}
	if(n=10 || n>10){
		q=(n-9)*2+9*2.2;
		cout<<q;
	}
    
} 

/**************************************************************
	Problem: 1303
	User: zhengzihao3
	Language: C++
	Result: Wrong Answer
****************************************************************/