



'''simple docstring'''

from collections import Counter







def     __UpperCamelCase					(				_lowercase       )			->      Optional[Any]:
	return sum(socks_by_color // 2 for socks_by_color in Counter(__a       ).values()       )


if __name__ == "__main__":
		import doctest

		doctest.testmod()

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





from __future__ import annotations

def       A_   (						__a  :					int		):

				"""simple docstring"""
				a__					   =		{1}
				a__					   =		[1]
				for _ in range(2			,		depth + 1		):
								a__					   =		[*previous_coefficients, 0]
								a__					   =		[0, *previous_coefficients]
								a__					   =		[]
								for x, y in zip(__a			,		__a		):
												coefficients.add(x + y		)
												previous_coefficients.append(x + y		)
				return coefficients

def       A_   (						__a  :					set[int]		):

				"""simple docstring"""
				a__					   =		set()
				for number in unique_coefficients:
								a__					   =		2
								a__					   =		number
								while divisor**2 <= copy_number:
												a__					   =		0
												while copy_number % divisor == 0:
																copy_number //= divisor
																multiplicity += 1
												if multiplicity >= 2:
																non_squarefrees.add(__a		)
																break
												divisor += 1

				return unique_coefficients.difference(__a		)

def       A_   (						__a  :					int = 51		):

				"""simple docstring"""
				a__					   =		get_pascal_triangle_unique_coefficients(__a		)
				a__					   =		get_squarefrees(__a		)
				return sum(__a		)


if __name__ == "__main__":
	print(f"""{solution() = }""")

