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

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int m = in.nextInt();
        System.out.println(minPaperCuts(n, m));
    }
    
    private static long minPaperCuts(int n, int m) {
        long[][] minCuts = new long[n + 1][m + 1];
        
        Arrays.fill(minCuts[0], 0);        
        for (int i = 0; i < n + 1; ++i) {
            minCuts[i][0] = 0;
        }
        
        for (int i = 1; i < n + 1; ++i) {
            minCuts[i][1] = i - 1;
        }
        
        for (int i = 1; i < m + 1; ++i) {
            minCuts[1][i] = i - 1;
        }
        
        for (int i = 2; i < n + 1; ++i) {
            for (int j = 2; j < m + 1; ++j) {
                long minSoFar = Long.MAX_VALUE;
                for (int vCutPos = 1; vCutPos <= j / 2; ++vCutPos) {
                    if (minCuts[i][j - vCutPos] + minCuts[i][vCutPos] < minSoFar)
                        minSoFar = minCuts[i][j - vCutPos] + minCuts[i][vCutPos];                    
                }
                
                for (int hCutPos = 1; hCutPos <= i / 2; ++hCutPos) {
                    if (minCuts[i - hCutPos][j] + minCuts[hCutPos][j] < minSoFar)
                        minSoFar = minCuts[i - hCutPos][j] + minCuts[hCutPos][j];
                }
                    
                minCuts[i][j] = minSoFar;
            }
        }
        
        return minCuts[n][m];
    }
}