from random import choice

questions = [ [i,j] for i in range(1,10) for j in range(1,10) ]
false_answers = []

while questions:
   q = choice(questions)
   del questions[questions.index(q)]

   answer = raw_input('%dx%d = ' % tuple(q))

   if int(answer) == q[0]*q[1]:
      print 'correct'
   else:
      print 'incorrect'
      false_answers.append(q)

print 'You have answered all questions!'