#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();

static (long d, long x, long y) ExtendedGCD(long a, long b)
{
    var (x0, y0, x1, y1) = (1L, 0L, 0L, 1L);
    while (b != 0)
    {
        var q = a / b;
        (a, b) = (b, a - q * b);
        (x0, y0, x1, y1) = (x1, y1, x0 - q * x1, y0 - q * y1);
    }
    return (a, x0, y0);
}

static long? ModDiv(long a, long b, long m)
{
    if (b == 0) throw new DivideByZeroException();
    var (d, t, _) = ExtendedGCD(b, m);
    if (a % d != 0) return null;
    if (d < 0) (d, t) = (-d, -t);
    var dm = m / d;
    var y = (long)((Int128)a / d * t % dm);
    if (y < 0) y += dm;
    return y;
}

var n = I<int>();
var k = I<int>();
var m = I<int>();
var bz = Range(n, I<int>);
var cz = Range(n, I<long>);

var s = 0L;
var (ri, rj) = (0, 0);
while (k > 0)
{
    var (b, c) = (bz[ri], cz[ri]);
    if (b <= k)
    {
        ri++;
        k -= b;
        s += c * b;
        s %= m;
        continue;
    }
    rj = k;
    s += c * rj;
    s %= m;
    break;
}
var (li, lj) = (0, 0);
var ans = 0;
if (s == 0) ans = 1;
while (ri < n)
{
    var (bl, cl) = (bz[li], cz[li]);
    var (br, cr) = (bz[ri], cz[ri]);
    var p = Math.Min(bl - lj, br - rj);
    lj += p;
    rj += p;
    if (lj == bl) (li, lj) = (li + 1, 0);
    if (rj == br) (ri, rj) = (ri + 1, 0);
    var d = (cr - cl) % m;
    if (d < 0) d += m;
    while (p > 0)
    {
        if (d == 0)
        {
            if (s == 0) ans += p;
            break;
        }
        if (s > 0)
        {
            var t = m - s;
            var k0q = ModDiv(t, d, m);
            if (k0q != null)
            {
                var k0 = (int)k0q.Value;
                if (k0 <= p)
                {
                    s = 0;
                    ans++;
                    p -= k0;
                }
            }
            if (s != 0)
            {
                s = (s + d * p) % m;
                break;
            }
        }
        {
            var k0q = ModDiv(m, d, m);
            if (k0q != null)
            {
                var k0 = (int)k0q.Value;
                if (k0 > 0)
                {
                    var q = p / k0;
                    ans += q;
                    p -= q;
                }
            }
            s = (s + d * p) % m;
            break;
        }
    }
}
Console.WriteLine(ans);