when I pass ['bbb', 'ccc', 'axx', 'xzz', 'xaa'] as words to the below function, it picks up only 'xzz' and not 'xaa' def front_x(words): # +++your code here+++ a = [] b = [] for z in words: if z.startswith('x'): words.remove(z) b.append(z) print 'z is', z print 'original', sorted(words) print 'new', sorted(b) print sorted(b) + sorted(words) Thanks, Deepti