use proconio::input;

fn main() {
    input! {
        h: usize, w: usize,
        mut a: [[usize; w]; h],
    }

    for i in 0..h - 1 {
        for j in 0..w - 1 {
            if a[i][j] == 1 {
                for di in 0..2 {
                    for dj in 0..2 {
                        a[i + di][j + dj] ^= 1;
                    }
                }
            }
        }
    }

    let mut ans = a.iter().flatten().sum::<usize>();
    let mut bottomright = 0;
    for di in 0..2 {
        for dj in 0..2 {
            bottomright += a[h - 2 + di][w - 2 + dj];
        }
    }
    if bottomright == 3 {
        ans -= 2;
    }

    println!("{ans}");
}