import java.util.Arrays;
import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {

	void run() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		char[][] s = new char[N][N];
		for (int i = 0; i < N; ++i) {
			s[i] = sc.next().toCharArray();
		}
		int ans = 0;
		{
			boolean f = true;
			for (int i = 0; i < N; ++i) {
				for (int j = 0; j < N; ++j) {
					if (i == 0 || i == N - 1 || j == 0 || j == N - 1) {
						f &= s[i][j] == '.';
					}
				}
			}
			if (f)
				ans = 4;
		}
		for (int t = 0; t < 2; ++t) {
			ans = Math.max(solve(s), ans);
			for (int i = 0; i < N; ++i) {
				for (int j = i + 1; j < N; ++j) {
					char tmp = s[i][j];
					s[i][j] = s[j][i];
					s[j][i] = tmp;
				}
			}
		}
		System.out.println(ans);
	}

	int solve(char[][] s) {
		int N = s.length;
		int ret = 0;
		for (int i = 0; i < N; i += N - 1) {
			for (int d = 0; d <= 1; ++d) {
				char[][] s2 = new char[N][N];
				for (int j = 0; j < N; ++j)
					for (int k = 0; k < N; ++k)
						s2[j][k] = s[j][k];
				boolean flag = true;
				ret = Math.max(ret, go(s2));
				for (int j = d; j < N - 1 + d; ++j) {
					flag &= s2[i][j] == '.';
					s2[i][j] = '#';
				}
				ret = Math.max(ret, (flag ? 1 : 0) + go(s2));
			}
		}
		return ret;
	}

	int go(char[][] s) {
		int ret = 0;
		int N = s.length;
		for (int i = 0; i < N; ++i) {
			boolean flag = true;
			for (int j = 1; j < N - 1; ++j) {
				flag &= s[j][i] == '.';
			}
			if (flag && (s[0][i] == '.' || s[N - 1][i] == '.')) {
				++ret;
			}
		}
		return ret;
	}

	public static void main(String[] args) {
		new Main().run();
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	void show(char[][] s) {
		int N = s.length;
		for (int i = 0; i < N; ++i) {
			for (int j = 0; j < N; ++j) {
				System.out.print(s[i][j]);
			}
			System.out.println();
		}
	}
}