



"""simple docstring"""


def 				_lowerCAmelCase   (     lowercase_		):

						# validate:
						if not isinstance(lowercase_	,			lowercase_		) or not all(
						    isinstance(lowercase_	,			lowercase_		) and item >= 0 for item in citations		):
												raise ValueError('The citations should be a list of non negative integers.'		)

						citations.sort()
						UpperCAmelCase    =				len(lowercase_		)

						for i in range(lowercase_		):
												if citations[len_citations - 1 - i] <= i:
																		return i

						return len_citations


if __name__ == "__main__":
				import doctest

				doctest.testmod()










"""simple docstring"""


from collections import Counter

def 				_lowerCAmelCase   (     lowercase_		):
						return sum(socks_by_color // 2 for socks_by_color in Counter(lowercase_		).values()		)


if __name__ == "__main__":
				import doctest

				doctest.testmod()

				snake_case_         = [int(x) for x in input("""Enter socks by color :""").rstrip().split()]
				print(f'''sock_merchant({colors}) = {sock_merchant(colors)}''')





