import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int count = 0;
		
		for (int i=1;i<=N;i++) {
		    if (i %2 != 0) {
		        count+=1;
		    }
		}
		
		double ans = (double) count/N;
		System.out.println(ans);
    
    }
}
/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