# page 66 EXAMPLE 3
# page 66 EXAMPLE 3
reset()
def solve(y):
    y1 = diff(y)
    y2 = diff(y1)
    if y2 * y - x * y1 == 0:
        return 'solution'
    else:
        return 'not a solution'
print solve(x**2)
print solve(1)
print solve(-x**2)
print solve(x**2 + 1)