a,b,c = gets.split.map(&:to_i) # 入力が複数の場合

red = a
blue = b
white = c
purple = 0

(1..white).each do |a|
  if red >= blue
    blue += 1
  else
    red += 1
  end
end

if red >= blue
  purple = blue
else
  purple = red
end

puts purple