#include <bits/stdc++.h>
#define LL long long
using namespace std;
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
LL n , m; 
int main()
{
	    scanf ("%lld %lld" , &n , &m);
	    printf ("%lld" , n * m - n - m);
		return 0;
}