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

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