s=set(['Adam','adam','Lisa','lisa','Bart','Paul'])
print s
print len(s)
print 'adam' in s
print 'lisa' in s
x='jan'
months=set(['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'])
if x in months:
	print 'input ok'
else:
	print 'inpur error'