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

public class No00000211_Main {

	public static void main(String[] args) throws IOException {

		int[] a = {2,3,5,7,11,13};
		int[] b = {4,6,8,9,10,12};

		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int cnt = 0;
		int k = Integer.parseInt(br.readLine());
		for(int i = 0; i < 6; i++) {
			for(int j = 0; j < 6; j++) {
				if(k == a[i] * b[j]) {
					cnt++;
				}
			}
		}
		System.out.println((double)cnt / 36);
	}
}