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


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