na982

#include <stdio.h>

int n, ret;

struct BOARD {
	int map[20][20];

	void rotate() {
		int temp[20][20];

		for (int y = 0; y < n; ++y) {
			for (int x = 0; x < n; ++x) {
				temp[y][x] = map[n - x - 1][y];
			}
		}

		for (int y = 0; y < n; ++y) {
			for (int x = 0; x < n; ++x) {
				map[y][x] = temp[y][x];
			}
		}
	}

	int get_max() {
		int ret = 0;
		for (int y = 0; y < n; ++y) {
			for (int x = 0; x < n; ++x) {
				if (ret < map[y][x]) {
					ret = map[y][x];
				}
			}
		}
		return ret;
	}

	void up() {
		int temp[20][20];

		for (int x = 0; x < n; ++x) {
			int flag = 0, target = -1;
			for (int y = 0; y < n; ++y) {
				if (map[y][x] == 0) {
					continue;
				}
				if (flag == 1 && map[y][x] == temp[target][x]) {
					temp[target][x] *= 2, flag = 0;
				}
				else {
					temp[++target][x] = map[y][x], flag = 1;
				}
			}
			for (++target; target < n; ++target) {
				temp[target][x] = 0;
			}
		}
		for (int y = 0; y < n; ++y) {
			for (int x = 0; x < n; ++x) {
				map[y][x] = temp[y][x];
			}
		}
	}
};

void dfs(BOARD cur, int count) {
	if (count == 5) {
		int candi = cur.get_max();
		if (ret < candi) {
			ret = candi;
		}
		return;
	}

	for (int dir = 0; dir < 4; ++dir) {
		BOARD next = cur;
		next.up();
		dfs(next, count + 1);
		cur.rotate();
	}
}

int main()
{
	BOARD board;
	scanf("%d", &n);
	for (int y = 0; y < n; ++y) {
		for (int x = 0; x < n; ++x) {
			scanf("%d", &board.map[y][x]);
		}
	}

	ret = 0;
	dfs(board, 0);
	printf("%d\n", ret);
	
	return 0;
}