import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Cutting_Paper_Squares solver = new Cutting_Paper_Squares();
        solver.solve(1, in, out);
        out.close();
    }

    static class Cutting_Paper_Squares {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int n = in.nextInt();
            int m = in.nextInt();
            out.println(Cuts(n, m));
        }

        public long Cuts(int n, int m) {
            if (n == 1) {
                return m - 1;
            }
            if (m == 1) {
                return n - 1;
            }
            long mincuts = 0;

            if (n > m) {
                int a = n / 2;
                int b = n - a;
                mincuts += (long) (1 + (Cuts(a, m) + Cuts(b, m)));
            } else {
                int a = m / 2;
                int b = m - a;
                mincuts += (long) (1 + (Cuts(n, a) + Cuts(n, b)));
            }


            return mincuts;
        }

    }
}