#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: wenda
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/