use std::io::Read;

fn main() {
    let mut s = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let w: u64 = itr.next().unwrap().parse().unwrap();
    let h: u64 = itr.next().unwrap().parse().unwrap();
    let n: u64 = itr.next().unwrap().parse().unwrap();

    let mut left = std::collections::HashMap::new();
    let mut right = std::collections::HashSet::new();
    for _ in 0..n {
        let s: u64 = itr.next().unwrap().parse().unwrap();
        let t: u64 = itr.next().unwrap().parse().unwrap();
        let num = left.entry(s).or_insert(0);
        *num += 1;
        right.insert(t);
    }

    let mut cnt: u64 = 0;
    let mut ans: u64 = 0;
    for &v in left.values() {
        cnt += 1;
        ans += h - v;
    }
    ans += (w - cnt) * (right.len() as u64);
    println!("{}", ans);
}