# include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;

const ll maxn = (ll)5e5;
const ll linf = (ll)1e17;

ll n, m;

int main(){
    cin >> n >> m;
    cout << n * m - 1;

    return 0;
}