Problem:
Grid

There is a n × n grid D where each cell contains either 1 or 0.

Your task is to create a program that takes the gird data as input and computes the greatest number of consecutive 1s in either vertical, horizontal, or diagonal direction.

For example, the consecutive 1s with greatest number in the figure below is circled by the dashed-line.

The size of the grid n is an integer where 2 ≤ n ≤ 255.

Input

The input is a sequence of datasets. The end of the input is indicated by a line containing one zero. Each dataset is formatted as follows:

n
D11 D12 ... D1n
D21 D22 ... D2n
.
.
Dn1 Dn2 ... Dnn

Output

For each dataset, print the greatest number of consecutive 1s.

Sample Input

5
00011
00101
01000
10101
00010
8
11000001
10110111
01100111
01111010
11111111
01011010
10100010
10000001
2
01
00
3
000
000
000
0

Output for the Sample Input

4
8
1
0

Solution in Haskell (judge verdict: Accepted)

import Control.Applicative
import Control.Monad
import Control.Monad.ST
import Data.Functor
import Data.Function
import Data.Monoid
import Data.Maybe
import Data.List
import qualified Data.Foldable as Foldable
import qualified Data.Set as Set
import qualified Data.Sequence as Sequence
import Data.List.Split
import Data.Bits
import Data.Char
import Data.Ix
import Data.Ratio
import Data.Ord
import Data.Tuple
--import Data.Array
import Data.Array.IArray
--import Data.Array.Unboxed
import Data.Array.MArray
import Data.Array.IO
import Data.Array.ST
import Data.IORef
import Data.STRef
-- import System.IO.Unsafe
 
readInt = read :: String -> Int
readInteger = read :: String -> Integer
readDouble = read :: String -> Double
getInt = readLn :: IO Int
getInts = map readInt . words <$> getLine
getInteger = readLn :: IO Integer
getIntegers = map readInteger . words <$> getLine
getDouble = readLn :: IO Double
sjoin :: (Show a) => [a] -> String
sjoin = unwords . map show
cond :: a -> a -> Bool -> a
cond t f c = if c then t else f
apply2 :: (a -> a -> b) -> [a] -> b
apply2 f [x,y] = f x y
apply3 :: (a -> a -> a -> b) -> [a] -> b
apply3 f [x,y,z] = f x y z
apply4 :: (a -> a -> a -> a -> b) -> [a] -> b
apply4 f [x,y,z,w] = f x y z w
fnBin :: (b -> c -> d) -> (a -> b) -> (a -> c) -> a -> d
fnBin op f g x = op (f x) $ g x
fnTuple :: (a -> b, a -> c) -> a -> (b, c)
fnTuple (f,g) a = (f a, g a)
replace :: (Eq a) => a -> a -> [a] -> [a]
replace x y = map (\z -> if z==x then y else z)
modifyArray :: (Ix i, MArray a e m) => a i e -> i -> (e -> e) -> m ()
modifyArray arr ix f = readArray arr ix >>= writeArray arr ix . f
dictCompare :: [a -> a -> Ordering] -> a -> a -> Ordering
dictCompare [] _ _ = EQ
dictCompare (f:fs) x y = let c = f x y in if c==EQ then dictCompare fs x y else c
binMap :: (a -> a -> b) -> [a] -> [b]
binMap f (x:xs@(y:_)) = f x y : binMap f xs
binMap _ _ = []
splitRec :: Int -> [a] -> [[a]]
splitRec _ [] = []
splitRec n xs = let (y,ys) = splitAt n xs in y : splitRec n ys
infixl 7 `divCeil`
divCeil :: Integral a => a -> a -> a
x `divCeil` y = (x+y-1) `div` y
count :: (a -> Bool) -> [a] -> Int
count = (length .) . filter
-- end of templete

f :: Int -> Array (Int, Int) Char -> (Int, Int) -> (Int, Int) -> Int
f n arr (dy,dx) from = g 0 0 from
  where
    g r t p@(y,x) 
      | inRange ((1,1), (n,n)) p = (if (arr!p == '1') then let nt = t+1 in g (max r nt) nt  else g r 0) (y+dy, x+dx)
      | otherwise = r

main = do
    n <- getInt
    when (n/=0) $ do
        fd <- replicateM n getLine
        let arr = listArray ((1,1), (n, n)) $ concat fd :: Array (Int,Int) Char
        let fn = f n arr in print $ maximum $ concat [[fn (0, 1) (y, 1)| y <- [1..n]], [fn (1, 0) (1, x) | x <- [1..n]], [fn (1, 1) (y, 1) | y <- [1..n]], [fn (1, 1) (1, x) | x <- [2..n]], [fn (1, -1) (1, x) | x <- [1..n]], [fn (1, -1) (y, n) | y <- [2..n]]]
        main