#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


long int make_cut(int n, int m) {
        
    if (n == 1 && m == 1) {
        return 0;
    }
    else if (n == 1) {
        return 1 + make_cut(1, m/2) + make_cut(1, m - m/2);    
    }
    else if (m == 1) {
        return 1 + make_cut(n/2, 1) + make_cut(n - n/2, 1);
    }
    else {
        return 1 + make_cut(n/2, m) + make_cut(n - n/2, m);
    }

}

int main() {

    long int n, m;
    
    cin >> n;
    cin >> m;
    
    cout << make_cut(n, m) << endl;
    
    return 0;
}