from math import sqrt
def kv(a,b,c):
    d=b*b-4*a*c
    if (d<0):
        print "d<0"
        return
    x1=(-b+sqrt(d))/(2*a)
    x2=(-b-sqrt(d))/(2*a)
    if (d==0):
        x1=-b/(2*a)
        print x1
    print  x1,x2
kv(2,-2,13)