#include<bits/stdc++.h>
using namespace std;
int main(){
	float s,q;
	cin>>s;
	if(s<10){
		q=s*2.2;
	}
	else{
		q=s*2.0;
	}
	printf("%.1f",q);
	return 0;
}

/**************************************************************
	Problem: 1303
	User: huangcanwu
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/