"""simple docstring"""







import importlib.metadata
import subprocess
import sys



def       A__    (	lowercase_     :	bool = False						)  ->							Tuple:
   __lowerCamelCase    		=					False
   if "IPython" in sys.modules:
      __lowerCamelCase    		=					'google.colab' in str(sys.modules['IPython'].get_ipython()						)

   if in_colab:
      if upgrade:
         __lowerCamelCase    		=					['pip', 'install', '-U', 'torch']
         subprocess.run(lowercase_      , check=lowercase_						)
      # get the current version of torch
      __lowerCamelCase    		=					importlib.metadata.version('torch'						)
      __lowerCamelCase    		=					torch_version[: torch_version.rindex('.'						)]
      __lowerCamelCase    		=					F'''https://storage.googleapis.com/tpu-pytorch/wheels/colab/torch_xla-{torch_version_trunc}-cp37-cp37m-linux_x86_64.whl'''
      __lowerCamelCase    		=					['pip', 'install', xla_wheel]
      subprocess.run(lowercase_      , check=lowercase_						)
   else:
      raise RuntimeError('`install_xla` utility works only on google colab.'						)







"""simple docstring"""







from collections import Counter



def       A__    (	lowercase_     :	list[int]						)  ->							int:
   return sum(socks_by_color // 2 for socks_by_color in Counter(lowercase_						).values()						)


if __name__ == "__main__":
     import doctest

     doctest.testmod()

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






