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


int main() {
    long long n,m;
    cin >> n >> m;
    long long ans = 0;
    ans += min(n,m)-1;
    ans += min(n,m)*(max(n,m)-1);
    cout << ans << endl;
    return 0;
}