#include<bits/stdc++.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	if(n>=30){
		printf("%.1f",1.0*n);
	}
	if((n<=29&&n>=20)==1){
		printf("%.1f",1.2*n);
	}
	if((n<=19&&n>=10)==1){
		printf("%.1f",1.5*n);
	}
	if(n<10){
		printf("%.1f",n*1.8);
	}
	return 0;
}

/**************************************************************
	Problem: 1304
	User: lvrenxiang
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/