#include<stdio.h>
void main()
{
	int n;
	double p;
	scanf("%d",&n);
	if(n>=30){ 
		p=n;
 	}else if(n>=20&&n<=29){
 		p=1.2*n;
	}else if(n>=10&&n<=19){
		p=1.5*n;
	}else{
		p=1.8*n;
	}
	printf("%.1f",p);
} 
/**************************************************************
	Problem: 1304
	User: admin
	Language: C
	Result: Accepted
	Time:25 ms
	Memory:1144 kb
****************************************************************/