#include <bits/stdc++.h>
using namespace std;
int a;
float s;
int main(){
      cin>>a;
	  if(a>=10){
	  s=a*2.0;	
	  }
	  if(a<10){
	  s=a*2.2;	
	  }
	  printf("%.1f",s);
	   return 0;
}
/**************************************************************
	Problem: 1303
	User: chenyichuen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/