fn main() {
    let mut nmq = String::new();
    std::io::stdin().read_line(&mut nmq).ok();
    let nmq: Vec<usize> = nmq.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nmq[0];
    let m = nmq[1];
    let q = nmq[2];
    let queries = (0..q).map(|_| {
            let mut temp = String::new();
            std::io::stdin().read_line(&mut temp).ok();
            let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
            (temp[0]-1, temp[1]-1)
        })
        .collect::<Vec<_>>();

    let mut relations = vec![vec![false; m]; n];
    for &(a, b) in queries.iter() {
        relations[a][b] = true;
    }
    let mut dp = vec![vec![0usize; m+1]; n+1];
    for i in 0..=n {
        for j in 0..=n {
            if i+1 <= n {
                dp[i+1][j] = dp[i+1][j].max(dp[i][j]);
            }
            if j+1 <= m {
                dp[i][j+1] = dp[i][j+1].max(dp[i][j]);
            }
            if i+1 <= n && j+1 <= m {
                dp[i+1][j+1] = dp[i+1][j+1].max(dp[i][j] + if relations[i][j] { 1 } else { 0 });
            }
        }
    }
    println!("{}", dp[n][m]);
}