Full decs task

In a casino, all the playing cards got mixed up, and some of them got lost.
You have to collect as many full decks as possible.

You get N mixed up French playing cards as your input.

The cards are of the following ranks:
2, 3, 4, 5, 6, 7, 8, 9, T, J, Q, K, A

The four suits are:
S (Spade), C (Club), H (Heart), D (Diamond)

The cards are given using their rank followed by their suit:

2 of Spades: 2S
Ace of Clubs: AC
10 of Hearts: TH

Write a function that will accept an array of cards and return the number of full decks contained in the array.

Examples:
a) ["9C", "KS", "AC", "AH", "8D", "4C", "KD", "JC", "7D", "9D", "2H", "7C", "3C", "7S", "5C", "6H", "TH"] -> 0

b) ["2S", "2C", "2D", "2H", "3S", "3C", "3D", "3H", "4S", "4C", "4D", "4H", "5S", "5C", "5D", "5H", "6S", "6C", "6D", "6H", "7S", "7C", "7D", "7H", "8S", "8C", "8D", "8H", "9S", "9C", "9D", "9H", "TS", "TC", "TD", "TH", "JS", "JC", "JD", "JH", "QS", "QC", "QD", "QH", "KS", "KC", "KD", "KH", "AS", "AC", "AD", "AH", "2S", "2C", "2D", "2H", "3S", "3C", "3D", "3H", "4S", "4C", "4D", "4H", "5S", "5C", "5D", "5H", "6S", "6C", "6D", "6H", "7S", "7C", "7D", "7H", "8S", "8C", "8D", "8H", "9S", "9C", "9D", "9H", "TS", "TC", "TD", "TH", "JS", "JC", "JD", "JH", "QS", "QC", "QD", "QH", "KS", "KC", "KD", "KH", "AS", "AC", "AD", "AH", "2S", "2C", "2D", "2H", "3S", "3C", "3D", "3H", "4S", "4C", "4D", "4H", "5S", "5C", "5D", "5H", "6S", "6C", "6D", "6H", "7S", "7C", "7D", "7H", "8S", "8C", "8D", "8H", "9S", "9C", "9D", "9H", "TS", "TC", "TD", "TH", "JS", "JC", "JD", "JH", "QS", "QC", "QD", "QH", "KS", "KC", "KD", "KH", "AS", "AC", "AD"] -> 2



def full_decks_count input
  res = input.inject({}) do |h, el|
    h[el] ||= 0
    h[el] += 1
    h
  end

  return 0 if res.count < 52
  res.values.min
end