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