cities = [
    { : ,                : 21.0  },
    { : ,                : 15.2  },
    { : , : 11.3  },
    { : , :  7.55 },
    { : ,            :  5.85 },
    { : ,    :  4.98 },
    { : ,        :  4.7  },
    { : ,           :  4.58 },
    { : ,              :  4.4  },
    { : ,           :  3.98 }
]

def first(query):
    return next(query, None)

print(
    first(index for index, city in enumerate(cities)
        if city['name'] == ),
    first(city['name'] for city in cities if city['population'] < 5),
    first(city['population'] for city in cities if city['name'][0] == 'A'),
    sep='\n')