use proconio::input;

fn main() {
    input! {
        h: usize, w: usize
    }

    let mut res = vec![vec!['X'; w]; h];
    for i in 0..h {
        for j in 0..w {
            if ((i / 2) + j) % 2 == 0 {
                res[i][j] = 'O';
            }
        }
    }

    let ans = res
        .iter()
        .map(|row| row.iter().collect::<String>())
        .collect::<Vec<_>>()
        .join("\n");
    println!("{ans}");
}