import java.util.Scanner;

public class No221 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int bunshi = 10000 - N;
		int bunbo = 10000 + 98*N;
		System.out.println((double)bunshi/bunbo * 100);
	}
}