#include <cstdio>

char s[2222][2222];

int main(void)
{
	bool ans_found = false;
	int h, w, i, j, k, ans = 0;

	scanf("%d %d" ,&h, &w);
	for (i = 1; i <= h; i++)
		scanf("%s" ,&s[i][1]);

	for (i = 1; i <= h && !ans_found; i++)
		for (j = 1; j <= w && !ans_found; j++)
			if (s[i][j] == '.')
			{
				int light = 1;

				for (k = i - 1; k >= 1; k--)
					if (s[k][j] == '#')
						break;
				light += i - k - 1;

				for (k = i + 1; k <= h; k++)
					if (s[k][j] == '#')
						break;
				light += k - i - 1;

				for (k = j - 1; k >= 1; k--)
					if (s[i][k] == '#')
						break;
				light += j - k - 1;

				for (k = j + 1; k <= w; k++)
					if (s[i][k] == '#')
						break;
				light += k - j - 1;

				if (ans < light)
					ans = light;

				if (ans == h + w - 1)
					ans_found = true;
			}

	printf("%d" ,ans);
	return 0;
}