#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    int n, m, cnt;
    string s;
    cin >> n >> m;
    cnt = n*m;
    for (int i = 0; i < n; i++){
        cin >> s;
        for (int j = 0; j < m; j++){
            if (s[j] == 'R') cnt--;
        }
    }
    cout << cnt << endl;
}