def INT():
    return int(input())


def MI():
    return map(int, input().split())


def LI():
    return list(map(int, input().split()))


N, M, P, Q = MI()
for i in range(Q):
    x, f = MI()
    a = P + f
    x_inv = pow(x, P - 2, P)
    y_min = (a * x_inv) % P
    if y_min == 0:
        y_min += P

    ans = 0
    if M > y_min:
        ans = (M - y_min) // P + int((M - y_min) % P != 0)
    if M == y_min:
        ans += 1

    print(ans)