#include <iostream>

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;

    int ret = 0;
    for (int i = 0; i < n; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < m; j++) {
            if (s[j] != 'R')ret++;
        }
    }
    
    cout << ret << endl;
    return 0;
}