#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Trim().Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

var n = I<int>();
var az = Range(n, I<long>);
var bz = Range(n, I<long>);

var saz = new long[n + 1];
var sbz = new long[n + 1];
for (var i = 0; i < n; i++)
{
    saz[i + 1] = saz[i] + az[i];
    sbz[i + 1] = sbz[i] + bz[i];
}

double pass = 1L << 60;
double fail = -pass;
for (var lp = 0; lp < 100; lp++)
{
    var mid = (pass + fail) / 2;
    var lz = new double[n + 1];
    var rz = new double[n + 1];
    rz[n] = saz[n] - sbz[n] * mid;
    for (var i = 1; i <= n; i++)
    {
        var f = saz[i] - sbz[i] * mid;
        lz[i] = Math.Min(lz[i - 1], f);
    }
    for (var i = n - 1; i >= 0; i--)
    {
        var f = saz[i] - sbz[i] * mid;
        rz[i] = Math.Max(rz[i + 1], f);
    }
    bool F()
    {
        for (var k = 0; k <= n; k++) if (lz[k] >= rz[k]) return true;
        return false;
    }
    if (F()) pass = mid;
    else fail = mid;
}

var ans = pass.ToString("F8");
Console.WriteLine(ans);