static int n;

static int[][] board;

static int[][] visited;

static int[][] dis;

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

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

static int count = 0;

static ArrayList<Integer> homeCount;

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(new Pointer(pointer.x, pointer.y));

visited[pointer.x][pointer.y] = 1;

int home = 1; // 단지 번호에 해당하는 집의 갯수

count++; // 단지 번호

dis[pointer.x][pointer.y] = count;

while (!queue.isEmpty()) {

Pointer current = queue.poll();

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

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

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

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

if (board[nx][ny] == 1 && visited[nx][ny] == 0) {

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

visited[nx][ny] = 1;

dis[nx][ny] = count;

home++;

}

}

}

}

homeCount.add(home);

}

public static void printAnswer() {

Collections.sort(homeCount);

System.out.println(homeCount.size());

for (Integer number : homeCount) {

System.out.println(number);

}

}

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

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

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

board = new int[n][n];

visited = new int[n][n];

dis = new int[n][n];

homeCount = new ArrayList<>();

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

char[] number = br.readLine().toCharArray();

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

board[i][j] = number[j] - 48;

}

}

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

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

if (board[i][j] == 1 && visited[i][j] == 0) {

Main_2667_BFS.BFS(new Pointer(i, j));

}

}

}

Main_2667_BFS.printAnswer();

}