static int n;

static int[][] board;

static int[][] watered; // 물에 잠긴 영역을 표시하기 위한 배열

static int[] dx = {0, 0, 1, -1};

static int[] dy = {1, -1, 0, 0};

static int answer = Integer.MIN_VALUE;

static class Pointer {

int x;

int y;

public Pointer(int x, int y) {

this.x = x;

this.y = y;

}

}

public static void BFS(Pointer pointer) {

Queue<Pointer> queue = new LinkedList<>();

queue.offer(pointer);

while (!queue.isEmpty()) {

Pointer current = queue.poll();

for (int i = 0; i < dx.length; i++) {

int nx = current.x + dx[i];

int ny = current.y + dy[i];

if (nx >= 0 && ny >= 0 && nx < n && ny < n && watered[nx][ny] == 0) {

watered[nx][ny] = 1;

queue.offer(new Pointer(nx, ny));

}

}

}

}

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

StringTokenizer st;

n = Integer.parseInt(br.readLine());

board = new int[n][n];

ArrayList<Integer> numberList = new ArrayList<>();

numberList.add(0);

for (int i = 0; i < n; i++) {

st = new StringTokenizer(br.readLine());

for (int j = 0; j < n; j++) {

board[i][j] = Integer.parseInt(st.nextToken());

if (!numberList.contains(board[i][j])) {

numberList.add(board[i][j]);

}

}

}

Collections.sort(numberList);

for (int number : numberList) {

watered = new int[n][n];

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

if (board[i][j] <= number) {

watered[i][j] = 1;

}

}

}

int count = 0;

for (int i = 0; i < n; i++) {

for (int j = 0; j < n; j++) {

if (watered[i][j] == 0) { // 물에 잠기지 않은 영역 bfs로 체크

Main_2468.BFS(new Pointer(i, j));

count++;

}

}

}

answer = Math.max(answer, count);

}

System.out.println(answer);

}