Students in a class are making towers of blocks. Each student makes a (non-zero) tower by stacking pieces lengthwise on top of each other. n of the students use pieces made of two blocks and m of the students use pieces made of three blocks.

The students don’t want to use too many blocks, but they also want to be unique, so no two students’ towers may contain the same number of blocks. Find the minimum height necessary for the tallest of the students' towers.

Input

The first line of the input contains two space-separated integers n and m (0 ≤ n, m ≤ 1 000 000, n + m > 0) — the number of students using two-block pieces and the number of students using three-block pieces, respectively.

Output

Print a single integer, denoting the minimum possible height of the tallest tower.

Examples

Input

1 3


Output

9


Input

3 2


Output

8


Input

5 0


Output

10

Note

In the first case, the student using two-block pieces can make a tower of height 4, and the students using three-block pieces can make towers of height 3, 6, and 9 blocks. The tallest tower has a height of 9 blocks.

In the second case, the students can make towers of heights 2, 4, and 8 with two-block pieces and towers of heights 3 and 6 with three-block pieces, for a maximum height of 8 blocks.
import java.io.*;
import java.util.StringTokenizer;

public class Main {
    private final InputReader in;
    private final PrintWriter out;

    public Main(final InputReader in, final PrintWriter out) {
        this.in = in;
        this.out = out;
    }

    private static PrintWriter getOutput(final String filename) throws IOException {
        if (filename == null || filename.isEmpty()) {
            return new PrintWriter(new OutputStreamWriter(System.out));
        } else {
            return new PrintWriter(new FileWriter(filename + ".out"));
        }
    }

    public static void main(final String[] args) throws NumberFormatException, IOException {
        final String filename = "";
        final long time = System.currentTimeMillis();
        try (final InputReader in = new InputReader(filename); final PrintWriter out = getOutput(filename)) {
            new Main(in, out).solve();
        }
//        System.err.println("Running time: " + (System.currentTimeMillis() - time));
    }

    private void solve() throws IOException {
        final long n = in.nextInt();
        final long m = in.nextInt();
        long l = 0;
        long r = 10000000;
        while (l < r) {
            final long mid = (l + r) / 2;
            final long count2 = mid / 2;
            final long count3 = mid / 3;
            final long common = Math.min(count2 * 2, count3 * 3) / 6;
            if (Math.max(0, n - (count2 - common)) + Math.max(0, m - (count3 - common)) <= common) {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        out.println(l);
    }

    private void assertTrue(final boolean t) {
        if (!t) throw new RuntimeException();
    }
}

class InputReader implements Closeable {
    private StringTokenizer st;
    private final BufferedReader in;

    public InputReader(final String filename) throws IOException {
        if (filename == null || filename.isEmpty())
            in = new BufferedReader(new InputStreamReader(System.in));
        else
            in = new BufferedReader(new FileReader(filename + ".in"));
    }

    public boolean hasNextToken() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            String line = in.readLine();
            if (line == null)
                return false;
            st = new StringTokenizer(line);
        }
        return true;
    }

    public String nextToken() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            String line = in.readLine();
            if (line == null)
                return null;
            st = new StringTokenizer(line);
        }
        return st.nextToken();
    }

    public String readLine() throws IOException {
        return in.readLine();
    }

    public int nextInt() throws NumberFormatException, IOException {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() throws NumberFormatException, IOException {
        return Long.parseLong(nextToken());
    }

    public double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextToken());
    }

    @Override
    public void close() throws IOException {
        in.close();
    }
}