Baekjoon-12100-2048 (Easy)

N = int(input())
board = []
for _ in range(N):
    board.append(list(map(int,input().split())))

def rot(arr):
    new_arr = []
    for j in reversed(range(N)):
        line = []
        for i in range(N):
            line.append(arr[i][j])
        new_arr.append(line)
    return new_arr

# 최대 5번 -> 4^5 = 2^10 = 1000개
def moveBlocks(board, dirs):
    new_board = []
    for _ in range(dirs):
        board = rot(board)

    for i in range(N):
        new_line = [0] * N
        new_idx = 0
        for j in range(N):
            if board[i][j] != 0:
                if new_line[new_idx] == board[i][j]:
                    new_line[new_idx] *= 2
                    new_idx += 1
                elif new_line[new_idx]==0:
                    new_line[new_idx] = board[i][j]
                else:
                    new_idx += 1
                    new_line[new_idx] = board[i][j]
        new_board.append(new_line)
    
    max_num = 0
    for i in range(N):
        max_num = max(max_num, *new_board[i])
    
    return new_board, max_num

def solve(count, board):
    if count == 4:
        max_result = 0
        for dirs in range(4):
            new_board, max_num = moveBlocks(board, dirs)
            max_result = max(max_result, max_num)
        return max_result
    else:
        max_result = 0
        for dirs in range(4):
            new_board, max_num = moveBlocks(board, dirs)
            max_ = solve(count+1, new_board)
            max_result = max(max_result, max_, max_num)
        return max_result

print(solve(0,board))