import math


def solve():
    X, N, d = [int(s) for s in input().split()]

    if math.gcd(X, d) >= 2:
        print("inf")
        return

    if X == 1:
        print(-1)
        return

    if N < X:
        print("inf")
        return

    print(X * (X + d) - X - (X + d))


if __name__ == "__main__":
    Q = int(input())

    for _ in range(Q):
        solve()