如下：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.LinkedList;
import java.util.Queue;
import java.util.StringTokenizer;

public class Main {
	static int ans = 0, n;
	static int[][] map;
	static int[] dx = { -1, 1, 0, 0 };
	static int[] dy = { 0, 0, -1, 1 };

	public static void main(String[] args) {
		solve();
		out.flush();
	}

	static void solve() {
		n = in.nextInt();
		map = new int[n][n];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				map[i][j] = in.nextInt();
			}
		}

		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				if (map[i][j] == 1) {
					ans++;
					bfs(i, j);
				}
			}
		}
		out.print(ans);

	}

	/**
	 * 第一个版本的BFS
	 * @param x
	 * @param y
	 */
	static void bfs(int x, int y) {
		Queue<int[]> queue = new LinkedList<>();
		queue.offer(new int[] { x, y });
		map[x][y] = 0;
		while (!queue.isEmpty()) {
			int[] cur = queue.poll();
			int curx = cur[0];
			int cury = cur[1];
			for (int i = 0; i < dx.length; i++) {
				int newx = curx + dx[i];
				int newy = cury + dy[i];
				if (!check(newx, newy) || map[newx][newy] != 1) {
					continue;
				}
				queue.offer(new int[] { newx, newy });
				map[newx][newy] = 0;
			}
		}

	}
	
	/**
	 * 另一个版本BFS
	 * @param x
	 * @param y
	 */
	static void bfs1(int x, int y) {
		Queue<Pair> queue = new LinkedList<>();
		queue.offer(new Pair(x, y));
		map[x][y] = 0;
		while (!queue.isEmpty()) {
			Pair curPair = queue.poll();
			int curx = curPair.x;
			int cury = curPair.y;
			for (int i = 0; i < dx.length; i++) {
				int newx = curx + dx[i];
				int newy = cury + dy[i];
				if (!check(newx, newy) || map[newx][newy] != 1) {
					continue;
				}
				queue.offer(new Pair(newx, newy));
				map[newx][newy] = 0;
			}
		}

	}

	static class Pair {
		int x;
		int y;

		public Pair(int x, int y) {
			super();
			this.x = x;
			this.y = y;
		}

	}

	/**
	 * DFS版本
	 * @param x
	 * @param y
	 */
	static void dfs(int x, int y) {
		for (int i = 0; i < dx.length; i++) {
			int newx = x + dx[i];
			int newy = y + dy[i];
			if (!check(newx, newy)) {
				continue;
			}
			if (map[newx][newy] != 1) {
				continue;
			}
			map[newx][newy] = 0;
			dfs(newx, newy);
		}
	}

	private static boolean check(int newx, int newy) {
		if (newx >= n || newy >= n || newx < 0 || newy < 0) {
			return false;
		}
		return true;
	}

	static FastReader in = new FastReader();
	static PrintWriter out = new PrintWriter(System.out);

	static class FastReader {
		static BufferedReader br;
		static StringTokenizer st;

		FastReader() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		Long nextLong() {
			return Long.parseLong(next());
		}
	}
}