#include<bits/stdc++.h>
using namespace std;
using Int = long long;
//INSERT ABOVE HERE
signed main(){
  Int n,m;
  cin>>n>>m;
  Int ans=0;
  for(Int i=0;i<n;i++){
    string s;
    cin>>s;
    ans+=m-count(s.begin(),s.end(),'R');
  }
  cout<<ans<<endl;
  return 0;
}