import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	int N = Integer.parseInt(br.readLine());
	int i = 1;
	double odd = 0.0000000000, even = 0.0000000000;

	while (i <= N) {
	    if (i % 2 == 0)
		even++;
	    else
		odd++;
	    i++;
	}
	System.out.println(odd / (odd + even));
    }
}
/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