matrix = Array.new(n = $<.gets.to_i) {$<.gets.split.map(&:to_i)}
max = -Float::INFINITY
memo = {}

try = ->(x, y, w, h) {
  return 0 if x >= n or y >= n or w <= 0 or h <= 0
  key = "#{x},#{y},#{w},#{h}"
  return memo[key] if memo[key]
  
  if h == 1 and w == 1
    num = matrix[y][x]
  else
    try.(x, y + 1, w, h - 1)
    try.(x, y    , w, h - 1)
    try.(x + 1, y, w - 1, h)
    try.(x    , y, w - 1, h)
    num = try.(x, y, 1, 1) + try.(x + 1, y, w - 1, 1) +
          try.(x, y + 1, 1, h - 1) + try.(x + 1, y + 1, w - 1, h - 1)
  end
  max = num if num > max
  memo[key] = num
}

try.(0, 0, n, n)
puts max
