#include <bits/stdc++.h>
using namespace std;
int main(){
	int n;
	float m;
	cin>>n;
	if(n<10){
		m=n*1.8;
		printf("%.1f",m);
	}else if(n>=10&&n<=19){
		m=n*1.5;
		printf("%.1f",m);
	}else if(n>=20&&n<=29){
		m=n*1.2;
		printf("%.1f",m);
	}else{
		m=n*1.0;
		printf("%.1f",m);
	}
	
}


/**************************************************************
	Problem: 1304
	User: 15159808820
	Language: C++
	Result: Accepted
	Time:17 ms
	Memory:2072 kb
****************************************************************/