#include<stdio.h>
char s[1003][1003];
int main()
{
	int n, m;
	scanf("%d %d", &n, &m);
	int i, j;
	for (i = 0; i < n; i++)
		scanf("%s", s[i]);
	int cnt_x[1003];
	for (j = 0; j < m; j++)
	{
		cnt_x[j] = 0;
		for (i = 0; i < n; i++)
			if (s[i][j] == 'x')
				cnt_x[j]++;
	}
	int ans = 0;
	for (i = 0; i < m; i++)
		if (ans <= cnt_x[i])
			ans = cnt_x[i] + 1;
	printf("%d\n", ans);
	return 0;
}