#include<bits/stdc++.h>
using namespace std;
int main(){
int i;
cin>>i;
        if(i>=10)printf("%.1f",i*2.0);
        else printf("%.1f",i*2.2);
         
}
/**************************************************************
	Problem: 1303
	User: 12345678
	Language: C++
	Result: Accepted
	Time:6 ms
	Memory:2072 kb
****************************************************************/