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

int num_of_cuts(int n,int m)
{
    if(n == 1) return m-1;
    if(m == 1) return n-1;
    if(n > m) return 1 + num_of_cuts(1,n) + num_of_cuts(m-1,n);
    else return 1+  num_of_cuts(1,m) + num_of_cuts(n-1,m);
}


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n,m;
    cin >> n >> m;
    cout << num_of_cuts(n,m);
    return 0;
}