a = 2
b = 4
c = 1
D = b**2 - 4*a*c
if(D<0):
    print("error")
else:
    if(D == 0):
        x = -b/(2*a)
        print(x)
    else:
            X1 = (-b + D**0.5) / (2*a)
            X2 = (-b - D**0.5) / (2*a)
            print("x1=")
            print(X1)
            print(";x2=")
            print(X2)