#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<map>
#define all(x) x.begin(),x.end()
#define pb push_back
#define ll long long 
#define P pair<int,int>
#define LP pair<ll,ll>
using namespace std;
int main() {
	int n, m;
	cin >> n >> m;
	int cnt = n * m;
	for (int i = 0; i < n; i++) {
		string s;
		cin >> s;
		for (int j = 0; j < m; j++) {
			if (s[j] == 'R') cnt -= 1;
		}
		}
	cout << cnt <<endl;
	return 0;
}