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

long long divide(long long w, long long h){
    if(w==1 && h==1) return 0;
    
    if(w==1) return h-1;
    if(h==1) return w-1;
    
    if(w>=h){
        if(w%2 == 0){
            return 1 + 2*divide(w/2,h);
        }
        else{
            return 1 + divide(w/2,h) + divide(w/2+1,h);
        }
    }
    else{
        if(h%2 == 0){
            return 1 + 2*divide(w,h/2);
        }
        else{
            return 1 + divide(w,h/2) + divide(w,h/2+1);
        }
    }
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    long long w,h;
    cin >> w >> h;
    
    if(w==1 && h==1) cout << 0;
    else if(w==1) cout << (h-1);
    else if(h==1) cout << (w-1);
    else{
        cout << divide(w,h);
    }
    return 0;
}