#include<bits/stdc++.h>
using namespace std;
int main(){
    int a;
    float b,c;
    cin>>a;
    if(a>=30){
    	b=1;
    	c=a*b;
        printf("%.1f",c);
    }if(a>=20&&a<=29){
    	b=1.2;
        c=a*b;
        printf("%.1f",c);
    }if(a>=10&&a<=19){
    	b=1.5;
        c=a*b;
        printf("%.1f",c);
    }if(a<10){
    	b=1.8;
        c=a*b;
        printf("%.1f",c);
    }
    
}
/**************************************************************
	Problem: 1304
	User: sucongyi
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/