import java.math.BigDecimal;
import java.util.Scanner;

public class No_285 {
public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	long D = sc.nextLong();
	sc.close();
	BigDecimal BDD = new BigDecimal(D);
	BigDecimal zei = new BigDecimal("0.08");
	BigDecimal ritsu = BDD.multiply(zei);
	BigDecimal Val = BDD.add(ritsu);
	System.out.println(Val);
}
}