#include<bits/stdc++.h>
#define mp make_pair
#define PII pair<int,int>
#define fi first
#define se second
#define pb push_back
using namespace std;

//********************************************
//Error tracking
#define show(args...) { vector<string> _v = split(#args, ','); err(_v.begin(), args); }

vector<string> split(const string& s, char c) {
    vector<string> v;
    stringstream ss(s);
    string x;
    while (getline(ss, x, c))
        v.emplace_back(x);
    return move(v);
}

void err(vector<string>::iterator it) {}
template<typename T, typename... Args>
void err(vector<string>::iterator it, T a, Args... args) {
    cerr << it -> substr((*it)[0] == ' ', it -> length()) << " = " << a << '\n';
    err(++it, args...);
}
//********************************************

long long sol,n,m;

int main()
{
    //freopen("input","r",stdin);
   // freopen("output","w",stdout);
    cin.sync_with_stdio(false);

    cin >> n >> m;
    if (n == 1 && m == 1) {cout << "0\n"; return 0;}
    sol =  m - 1 + 1LL*m*(n - 1);
    cout << sol << "\n";    
    return 0;   
}