import java.io.*;

class Process {
    private int K;

    Process(int K) {
        this.K = K;
    }

    double getResult() {
        int[] primes     = {2, 3, 5, 7, 11, 13};
        int[] composites = {4, 6, 8, 9, 10, 12};

        var numsOfDice = new int[primes.length][composites.length];
        for(int p = 0; p < primes.length; p++) {
            for(int c = 0; c < composites.length; c++) {
                numsOfDice[p][c] = primes[p] * composites[c];
            }
        }

        int count = 0;
        for(int i = 0; i < numsOfDice.length; i++) {
            for(int j = 0; j < numsOfDice[0].length; j++) {
                if(numsOfDice[i][j] == K) {
                    count++;
                }
            }
        }

        return ((double)count / (numsOfDice.length * numsOfDice[0].length));
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        var bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        var printWriter    = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

        // 入力
        int K = Integer.parseInt(bufferedReader.readLine().trim());
        
        // 処理および出力
        printWriter.println((new Process(K)).getResult());
        
        bufferedReader.close();
        printWriter.close();
    }
}