a = 30

b = 1

if a >=10:

    a = 20

elif a>=20:

    a = 30

elif a>=30:

    b = a

else:

    b = 0

print('a={}, b={}'.format(a,b))

frame = [[1,2,3],[4,5,6],[7,8,9]]

rgb = frame[::-1]

print(rgb)

while x:

    x -= 1

    if not x%2:

        print(x,end = '')

else:

    print(x)

x = ['90','87','90']

n = 90

print(x.count(n))

for i in "the number changes":

    if i == 'n':

        break

    else:

        print( i, end= "")

ls =list("the sky is blue")

a = ls.index('s',5,10)

print(a)

d = {"zhang":"China", "Jone":"America", "Natan":"Japan"}

for k in d:

    print(k, end="")