pub fn make_arr(s: &str) -> Vec<i32> {
    s.trim_matches(&['[', ']'][..])
        .split(',')
        .map(|x| {
            let x = x.trim();
            if x == "null" {
                -1
            } else {
                x.parse::<i32>().unwrap()
            }
        })
        .collect()
}

pub fn make_matrix(s: &str) -> Vec<Vec<i32>> {
    s.trim_matches(&['[', ']'][..])
        .split("],[")
        .map(|row| {
            row.trim_matches(&['[', ']'][..])
                .split(',')
                .map(|x| x.trim().parse::<i32>().unwrap())
                .collect()
        })
        .collect()
}