output_description: Print the answer.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      N M
attempt: n,m = gets.chomp.split.map(&:to_i)
  if n > m / 2
    p m / 2
  else
    p (m+2*n) / 4
  end
problem_description: Statement
  
  Snuke loves puzzles.
  
  Today, he is working on a puzzle using `S`\- and `c`-shaped pieces. In this
  puzzle, you can combine two `c`-shaped pieces into one `S`-shaped piece, as
  shown in the figure below:
  
  ![9b0bd546db9f28b4093d417b8f274124.png](https://atcoder.jp/img/arc069/9b0bd546db9f28b4093d417b8f274124.png)
  
  Snuke decided to create as many `Scc` groups as possible by putting together
  one `S`-shaped piece and two `c`-shaped pieces.
  
  Find the maximum number of `Scc` groups that can be created when Snuke has N
  `S`-shaped pieces and M `c`-shaped pieces.
samples: [{"input": "1 6", "output": "2\n    \n\nTwo `Scc` groups can be created as follows:\n\n  * Combine two `c`-shaped pieces into one `S`-shaped piece\n  * Create two `Scc` groups, each from one `S`-shaped piece and two `c`-shaped pieces\n\n* * *"}, {"input": "12345 678901", "output": "175897"}]