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

int main() {
  int N, M;
  cin >> N >> M;
  int ans = 0;
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < M; j++) {
      char c;
      cin >> c;
      if (c != 'R') ans++;
    }
  }

  cout << ans << "\n";
}