#include <iostream>
#include <vector>
#include <algorithm>
#include <numeric>
using namespace std;
long long n, m, sum, type = 0;
void read()
{
    cin >> n >> m;
}
long long Cal (long long a, long long b)
{
    return (a + b)*(b - a + 1)/2;
}
void solve()
{
    if (n > 1)
    {
        sum += n - 1;
    }
    if (m > 2)
    {
        sum += m - 2;
    }
    --n;
    m -= 2;
    if (n > 0 && m > 0)
    {
       if (n <= m)
       {
          int t = n - 1;
          sum += Cal(1, t) + Cal (m - t, m - 1);
       }
       else
       {
           int t = m;
           sum += Cal(n - t, n - 1) + Cal (1, m - 1);
       }
    }
    cout << sum;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    read();
    solve();
}