#include <bits/stdc++.h>
using namespace std;
unsigned long long int cnt = 0;
char ch[710];
int a[710][710],m;
bool vis[710][710];
struct Node
{
	int x, y;
};
int d[9][2] = {{0,0},{-1,0},{0,-1},{0,1},{1,0},{-1,-1},{-1,1},{1,-1},{1,1}};
bool legal(int x,int y)
{
	return !(x < 1 || x > m || y < 1 || y > m);
}
void conn(int sx, int sy)
{
	queue<Node> q; q.push({sx, sy});
	vis[sx][sy] = true;
	while(!q.empty())
	{
		Node c = q.front(); q.pop();
		for(int i = 1; i < 9; ++i)
		{
			int x = c.x + d[i][0], y = c.y + d[i][1];
			if(legal(x, y) && a[x][y] && !vis[x][y])
			{
				q.push({x, y});
				vis[x][y] = true;
			}
		}
	}
}
int main()
{
	freopen("common.in","r",stdin);
	freopen("common.out","w",stdout);
	cin >> m;
	for(int i = 1;i <= m;i++)
	{
		cin >> ch;
		for(int j = 1;j <= m;j++)
		{
			a[i][j] = ch[j-1] - '0';
		}
	}
	for(int i = 1;i <= m;i++)
	{
		for(int j = 1;j <= m;j++)
		{
			if(a[i][j] && !vis[i][j])
			{
				conn(i,j);
				cnt++;
			}
		}
	}
	cout << cnt << endl;
}