#include<bits/stdc++.h>

#define INF 1e9
#define llINF 1e18
#define MOD 1e9+7
#define pb push_back
#define mp make_pair 
#define F first
#define S second
#define ll long long
using namespace std;
int main(){
  int n,m;cin>>n>>m;
  int ans=0;
  for(int i=0;i<n;i++){
    string s;cin>>s;
    for(int j=0;j<m;j++)
      ans+=(s[j]!='R');
  }
  cout<<ans<<endl;
  return 0;
}