def gcd(a, b):
    while b:
        a, b = b, a % b
    return a

def find_gcm_less_than_x(a, b, c, x):
    gcd_ab = gcd(a, b)
    gcm = (gcd(gcd_ab, c))
    
    if gcm < x:
        return gcm
    else:
        return -1

def main():
    T = int(input())
    for _ in range(T):
        a, b, c, x = map(int, input().split())
        result = find_gcm_less_than_x(a, b, c, x)
        print(result)

if __name__ == "__main__":
    main()