#include <bits/stdc++.h>
using namespace std;

int main()
{
	int N, M;
	cin >> N >> M;
	vector<string> A( N );
	for( int i = 0; i < N; i++ ) {
		cin >> A[i];
	}

	int ans = 0;
	for( int i = 0; i < N; i++ ) {
		for( int j = 0; j < M; j++ ) {
			if( A[i][j] != 'R' ) ans++;
		}
	}

	cout << ans << endl;
}