#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 */   
    unsigned long long m, n, k;
    cin >> m;
    cin >> n;
    
    k = m*n;
    cout<<k-1;
    
    return 0;
}