input: Write a function to convert a JSON string into a dictionary of dictionaries where keys are employee names and values are their ages.
  assert convert_json_to_dict('{"employees":[{"name":"John Smith","age":35},{"name":"Jane Doe","age":20},{"name":"John Doe","age":25}]}') == {'employees': {'John Smith': 35, 'Jane Doe': 20, 'John Doe': 25}}
  assert convert_json_to_dict('{"employees":[{"name":"Alice","age":30},{"name":"Bob","age":22}]}') == {'employees': {'Alice': 30, 'Bob': 22}}
  assert convert_json_to_dict('{"employees":[{"name":"Charlie","age":28},{"name":"David","age":24},{"name":"Eva","age":32}]}') == {'employees': {'Charlie': 28, 'David': 24, 'Eva': 32}}
output: import json
  
  def convert_json_to_dict(json_string):
      data = json.loads(json_string)
      result = {'employees': {}}
      for employee in data['employees']:
          result['employees'][employee['name']] = employee['age']
      return result