#include<bits/stdc++.h>
using namespace std;
int main(){

	int n;
	cin>>n;
	if(n>10){
		cout<<fixed<<setprecision(1)<<n*2.0;
	}
	if(n<10){
		cout<<fixed<<setprecision(1)<<n*2.2;
	}

	return 0;
}

/**************************************************************
	Problem: 1303
	User: huangyaojie3
	Language: C++
	Result: Accepted
	Time:11 ms
	Memory:2072 kb
****************************************************************/