category = {}
category['easy'] = ['cat', 'hat', 'dog', 'bird', 'frog', 'snake', 'plane',
    'bus', 'car', 'boat']
category['hard'] = ['valetudinarian', 'hungarian', 'rastafarian',
    'vegetarian', 'carnivore', 'omnivore', 'herbivore', 'bangalore', 'chapati']