use std::io;
use std::io::prelude::*;

fn main() {
    let stdin = io::stdin();
    let mut stdin_it = stdin.lock().lines();

    let _in: Vec<_> = stdin_it.next().unwrap().unwrap().split_whitespace().map(|x| x.parse::<u64>().unwrap()).collect();
    println!("{}", _in[0] * _in[1] - 1);
}