fn array_maximal_adjacent_difference(a: &[i64]) -> i64 {
    let mut dif = 0;
    for i in 1..a.len().saturating_sub(1) {
        dif = dif.max((a[i] - a[i - 1]).abs()).max((a[i] - a[i + 1]).abs());
    }

    dif
}