// yukicoder: No.712 赤旗
// 2019.5.2 bal4u

#include <stdio.h>

#if 1
#define gc() getchar_unlocked()
#define pc(c) putchar_unlocked(c)
#else
#define gc() getchar()
#define pc(c) putchar(c)
#endif
int in()   // 整数の入力（負数に対応）
{
	int n = 0, c = gc();
	do n = 10*n + (c & 0xf), c = gc(); while (c >= '0');
	return n;
}

int main()
{
	int N, M, m, s;
	
	s = 0, N = in(), M = in();
	while (N--) {
		m = M; while (m--) if (gc() != 'R') s++;
		gc();
	}
	printf("%d\n", s);
	return 0;
}