#include <iostream>

#include <vector>

#include <algorithm>

using namespace std;

int N;

int board[25][25];

bool visited[25][25];

vector<int> houses;

int dfs(int i, int j) {

int res = 1;

visited[i][j] = true;

if (i - 1 >= 0 && board[i - 1][j] == 1 && !visited[i - 1][j]) res += dfs(i - 1, j);

if (j - 1 >= 0 && board[i][j - 1] == 1 && !visited[i][j - 1]) res += dfs(i, j - 1);

if (i + 1 < N && board[i + 1][j] == 1 && !visited[i + 1][j]) res += dfs(i + 1, j);

if (j + 1 < N && board[i][j + 1] == 1 && !visited[i][j + 1]) res += dfs(i, j + 1);

return res;

}

int main()

{

int i, j;

int count;

cin >> N;

for (i = 0; i < N; i++) {

string tmp;

cin >> tmp;

for (j = 0; j < N; j++) {

if (tmp[j] == '1') board[i][j] = 1;

else board[i][j] = 0;

visited[i][j] = false;

}

}

for (i = 0; i < N; i++) {

for (j = 0; j < N; j++) {

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

count = dfs(i, j);

houses.push_back(count);

}

}

}

cout << houses.size() << "\n";

sort(houses.begin(), houses.end());

for (int house : houses) {

cout << house << "\n";

}

}