535C - Tavas and Karafs - CodeForces Solution

f = lambda: map(int, input().split())
A, B, n = f()
k = 0.5
for i in range(n):
    l, t, m = f()
    b = A / B + l - k
    c = b - k - (m * t) / B
    r = min(l + int((b * b - 2 * c) ** k - b), (t - A) // B + 1)
    print(-1 if r < l else r)