#include <bits/stdc++.h>
 using namespace std;

#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define LL long long int
#define pb push_back 
#define mp make_pair
#define PII pair<int,int>
#define test int t;cin>>t;while(t--)
#define ff first
#define ss second
#define input(a,n) for(i=0;i<n;i++)cin>>a[i];

 
int main() {
    fast
    LL n,b,i,j,k,z,x=0,y=0,sum=1e18,p,q,l,T,m,ans=0;
    double xx,yy;
   bool f;
   string s;
    
     cin>>n>>m;
   
    if(n==1 && m==1)
        cout<<0;
    else if(n==1)
        cout<<m-1;
        else if(m==1)
        cout<<n-1;
        else
        {
        	x=min(n,m);
        	y=max(n,m);
        	ans=y-1;
        	ans=ans+(x-1)*y;
        	cout<<ans;
        }
     
     return 0;
}