#include <bits/stdc++.h>
#define ll long long

using namespace std;

int main()
{
	//freopen("i.txx","r",stdin);
	ll n,m;
	cin>>n>>m;
	if(n==1 or m==1)
	{
		if(n==1 and m==1)
			cout<<"0"<<endl;
		else if(n==1)
			cout<<m-1<<endl;
		else
			cout<<n-1<<endl;
	}
	else
	{
		ll tp = (m-1) + m*(n-1);
		cout<<tp<<endl;
	}
	return 0;
}