#include<bits/stdc++.h>
using namespace std;
int main(){
    int g;
    float q;
    cin>>g;
    if(g>=30){
        q=g;
    }else if(g>=20&&g<=29){
        q=g*1.2;
    }else if(g>=10&&g<=19){
        q=g*1.5;
    }else{
        q=g*1.8;
    } 
    printf("%.1f",q);
    return 0;
}
/**************************************************************
	Problem: 1304
	User: lijinkai
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/