(x,y,r)=gets.chomp.split.map {|x| x.to_i}

def ufo(x,y,r)
  nx = x.abs + r / Math.sqrt(2)
  ny = y.abs + r / Math.sqrt(2)
  # dy = -1 * dx + m
  dx = nx
  dy = ny
  m = dy + dx
  return m.ceil
end

puts ufo(x,y,r)

# 1 : Math.sqrt(2) = ? : r
# 1.414 * ? = r