s =set([1,2,3,4,234,243,4,4,])

s.add(2)

s.add(4)

s.remove(4)

print(s)

s1 =set([1,2,3,4,5,])

s2 =set([2,3,4,5,6,7,8])

print(s1 | s2)

a ='abc'

b = a.replace('a','A')

print(a)

print(b)