import java.io.IOException;
import java.util.Scanner;
 
public class Main {
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();

		int cnt = 0;
		for (int i = 1; i <= n; i++) {
			if (i % 2 != 0) {
				cnt++;
			}
		}

		System.out.println((double)cnt / n);
	}
	
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz