T = int(input())

for i in range(T):
    s, c, N = [int(num) for num in input().split()]
    k_data = []
    for j in range(N):
        g, l = [int(num) for num in input().split()]
        k_data.append((g, l))

    all_s = [s]

    for day_num in range(len(k_data)):
        _, l = k_data[day_num]

        if day_num >= 1:
            _, l = k_data[day_num - 1]
            s -= l
        if day_num >= 2:
            _, l = k_data[day_num - 2]
            s -= l
        if day_num >= 3:
            g, _ = k_data[day_num - 3]
            s += g

        all_s.append(s)

    day_d = -1
    for idx, k in enumerate(all_s):
        if k < c:
            day_d = idx + 1
            break
        else:
            c += 1

    print('Ok' if day_d == -1 or day_d > N else day_d)