def solveCubicEquation(a, b):
    '''Solve cubic equation x^3 + a*x + b = 0'''
    a = complex(a)
    b = complex(b)
    d = (27*b)**2 + 4*27*a**3
    y = (-27*b + d**(1/2))/54
    u = y**(1/3)
    v = -a/(3*u)
    x = u + v
    return x
    
if __name__ == "__main__":
    while True:
        print("Solve cubic equation x^3 + a*x + b = 0")
        try:
            s = input("a: ")
            a = complex(s)
            s = input("b: ")
            b = complex(s)
            x = solveCubicEquation(a, b)
            print("Solution:", x)
        except ValueError:
            if s == 'q':
                break
            print("Incorrect format of a number")