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


int main() {
   long  int n ,t;
       
     cin>>n>>t;
    if(n==t && (n%2==0 && t%2==0))
        cout<<(n-1)*(t-1)<<endl;
    else
        {
        //if(n==t && (n%2!=0 && t%2!=0))
            
      cout<<n*t-1<<endl;
    }/* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}