#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;
    cin>>n;
    float s;
    if(n>=30) s=n*1.0;
    else if(n>=20&&n<=29) s=n*1.2;
    else if(n>=10&&n<=19) s=n*1.5;
    else s=n*1.8;
    printf("%.1f",s);
}
/**************************************************************
	Problem: 1304
	User: linyuhang
	Language: C++
	Result: Accepted
	Time:23 ms
	Memory:2072 kb
****************************************************************/