#include<bits/stdc++.h> 
using namespace std;
int main(){
	float a,b,c;
	cin>>a;
	if(a>10.0 || a==10.0){
		b=2.0*a;
		printf("%.1f",b);
	} 
	    
	if(a<10.0){
		c=2.2*a;
		printf("%.1f",c);
	}
	       
		 
	return 0;
}
/**************************************************************
	Problem: 1303
	User: cyp
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/