#include <bits/stdc++.h>
#define rep(i,n) for (int i=0; i<(n); ++i)
using namespace std;
using ll=long long;
int main(){
    int n,m;
    cin>>n>>m;
    int ans=n*m;
    rep(i,n){
        string s;
        cin>>s;
        rep(i,m){
            if(s[i]=='R')ans--;
        }
    }
    cout<<ans<<endl;
}