#include<stdio.h>
int main()
{
	int n, m;
	scanf("%d %d", &n, &m);
	char a[55][55];
	int i, j;
	for (i = 0; i < n; i++)
		scanf("%s", a[i]);
	int ans = n * m;
	for (i = 0; i < n; i++)
		for (j = 0; j < m; j++)
			if (a[i][j] == 'R')
				ans--;
	printf("%d\n", ans);
	return 0;
}