#include<bits/stdc++.h>
using namespace std;
int main(){
    float n,h=0;
    cin>>n;
    if(n>=30) {
        h=n*1.0;
    }
    else if(n<=29&&n>=20){
        h=n*1.2;
    }
    else if(n>=10&&n<=19){
        h=n*1.5;
    }  
    else {
        h=n*1.8;
    }
        printf("%.1f",h);
    return 0;
}
/**************************************************************
	Problem: 1304
	User: binzicheng1
	Language: C++
	Result: Accepted
	Time:26 ms
	Memory:2072 kb
****************************************************************/