a, b, c, d = list(map(int, input().split()))
for i in range(1, abs(d) + 1):
    if d % i == 0:
        if a * (i ** 3) + b * (i ** 2) + c * i + d == 0:
            print(i)
            break
        elif a * ((-i) ** 3) + b * (i ** 2) + c * (-i) + d == 0:
            print(-i)
            break