#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float q;
    cin>>n;
    if (n>=30) {
        q=n*1.0;
    }
	else if (20<=n && n<=29){
        q=n*1.2;
    }
    else if (10<=n && n<=19){
    	q=n*1.5;
	}
	else{
		q=n*1.8;
	}
    printf("%.1f",q);
    return 0;
}
/**************************************************************
	Problem: 1304
	User: xiaojingxuan
	Language: C++
	Result: Accepted
	Time:21 ms
	Memory:2072 kb
****************************************************************/