import java.util.Scanner;
import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        //コード
        Scanner scanner = new Scanner(System.in);
        int n = Integer.parseInt(scanner.next());

        int num = 0;
        for(int i= 0; i <= n; i++) {
            if (i%2 != 0) {
                num++;
            }
        }
        //double a = (double) num / n;
        double result = (double)num / n;

        System.out.println(result);
    }
}
/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