#include<bits/stdc++.h>
using namespace std;
int main(){
    int s;
    float q;
    cin>>s;
    if(s>=10){
    	q=s*2;
    }else{
    	q=s*2.2;
    }
    printf("%.1f",q);
}

/**************************************************************
	Problem: 1303
	User: xuezihong1
	Language: C++
	Result: Accepted
	Time:10 ms
	Memory:2072 kb
****************************************************************/