#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };

    ($next:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        #[cfg(debug_assertions)]
        writeln!(&mut std::io::stderr(), concat!("[DEBUG] ", $(stringify!($a), "={:?} "),*), $($a),*);
    }
}

#[allow(unused_imports)]
use std::cmp::{min, max};
#[allow(unused_imports)]
use std::io::{stdout, stdin, BufWriter, Write};

fn main() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }

    input!{
      n: usize,
      aa: [usize; n],
      mut bb: [usize; n],
    }

    let mut ans = 0u64;
    let mut ok = 0;
    let mut q = std::collections::VecDeque::new();

    for i in 0..n {
        if aa[i] == bb[i] {
            ok += 1;
            continue;
        }

        let xi = if i == 0 { n-1 } else { i-1 };
        let yi = i;
        let zi = if i == n-1 { 0 } else { i+1 };

        let x = bb[xi];
        let y = bb[yi];
        let z = bb[zi];

        if y  > (x + z) {
            q.push_back(i);
        }
    }

    while q.len() > 0 {
        let i = q.pop_front().unwrap();
        if aa[i] == bb[i] {
            continue;
        }

        let xi = if i == 0 { n-1 } else { i-1 };
        let yi = i;
        let zi = if i == n-1 { 0 } else { i+1 };

        let x = bb[xi];
        let y = bb[yi];
        let z = bb[zi];

        if y <= (x + z) {
            continue;
        }
        if aa[i] > y {
            return puts!("{}\n", -1);
        }
        let dy = x + z;
        if (y-aa[i]) % dy == 0 {
            ans += ((y - aa[i]) / dy) as u64;
            bb[i] = aa[i];
            ok += 1;
            q.push_back(xi);
            q.push_back(zi);
        } else {
            let sub = y / dy * dy;
            bb[i] -= sub;
            if sub == 0 {
                unreachable!()
            }
            ans += (y/dy) as u64;
            q.push_back(xi);
            q.push_back(zi);
        }
    }

    // debug!(ok, bb);
    if ok == n {
        return puts!("{}\n", ans);
    } else {
        return puts!("{}\n", -1);
    }
}


Measured memory_bytes: 10492