#include<bits/stdc++.h>
using namespace std;
int main(){
	int a;
	float b;
	cin>>a;
	if(a>=10){
		b=a*2.0;
	}
	if(a<10){
		b=a*2.2;
	} 
	printf("%.1f",b);
}
/**************************************************************
	Problem: 1303
	User: huanglingkai
	Language: C++
	Result: Accepted
	Time:13 ms
	Memory:2072 kb
****************************************************************/