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