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


int main() {
   unsigned long int n,m;
   cin>>n>>m;
    if(n<m)
        n=n+m-(m=n);
    cout<<(n-1)*m;
    return 0;
}