import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int p = sc.nextInt();
        int c = sc.nextInt();
        int[] primes = new int[]{2, 3, 5, 7, 11, 13};
        int[] notprimes = new int[]{4, 6, 8, 9, 12};
        ArrayDeque<Double> deq = new ArrayDeque<>();
        deq.add(1.0);
        for (int i = 0; i < p; i++) {
            ArrayDeque<Double> next = new ArrayDeque<>();
            while (deq.size() > 0) {
                double x = deq.poll();
                for (int y : primes) {
                    next.add(x * y);
                }
            }
            deq = next;
        }
        for (int i = 0; i < c; i++) {
            ArrayDeque<Double> next = new ArrayDeque<>();
            while (deq.size() > 0) {
                double x = deq.poll();
                for (int y : notprimes) {
                    next.add(x * y);
                }
            }
            deq = next;
        }
        double sum = 0;
        while (deq.size() > 0) {
            sum += deq.poll();
        }
        System.out.println(new java.math.BigDecimal(sum / Math.pow(6, p + c)).toPlainString());
    }
}
class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}