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

public class Main {
	public static void main(String[] args) {
		BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
		int[] prime = { 2, 3, 5, 7, 11, 13 };
		int[] compo = { 4, 6, 8, 9, 10, 12 };
		try {

			int K = Integer.parseInt(read.readLine());

			double ans = 0;
			for (int i = 0; i < 6; ++i) {
				for (int j = 0; j < 6; ++j) {
					if (prime[i] * compo[j] == K) {
						ans += 1.0 / 36;
					}
				}
			}

			System.out.println(ans);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}