import math
def quadratic_equation(a, b, c):
z = b**2 - 4.0 * a * c
if z < 0:
return None
elif z == 0:
return -b / (2.0 * a)
else:
x = (-b + math.sqrt(z)) / (2.0 * a)
y = (-b - math.sqrt(z)) / (2.0 * a)
return x, y
def move(n, a, b, c):
if n==1:
print a,'-->',c,'\n'
else:
move(n-1, a, c, b)
print a,'-->',c,'\n'
move(n-1, b, a, c)
return
move(4, 'A', 'B', 'C')
