#include<bits/stdc++.h>
using namespace std; 
int main(){
    int n;
    cin>>n;
    if(n>=30) printf("%.1f",1.0*n);
	else if(n>=20&&n<=29) printf("%.1f",1.2*n);
    else if(n>=10&&n<=19) printf("%.1f",1.5*n);
    else printf("%.1f",1.8*n);
    return 0;
}
/**************************************************************
	Problem: 1304
	User: panjinyan
	Language: C++
	Result: Accepted
	Time:24 ms
	Memory:2072 kb
****************************************************************/