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


int main() {
    long long int n,m,s=0;
    cin>>n>>m;
    s+=min(n,m)-1;
    s+=(max(n,m)-1)*min(n,m);
        
    cout<<s;
    
    
}