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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    
    long n, m; // height & width
    cin >> n >> m; // 
    long total;
    
    total = (n * m) - 1;
    cout << total;
    return 0;
}