#include <bits/stdc++.h>
#define rep(i,n)for(int i=0;i<(n);i++)
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3f
#define EPS (1e-10)
using namespace std;
typedef long long ll;
typedef pair<int,int>P;

signed main(){
	int n,m;scanf("%d%d",&n,&m);
	int cnt=n*m;
	rep(i,n){
		string s;cin>>s;
		for(char c:s){
			if(c=='R')cnt--;
		}
	}
	cout<<cnt<<endl;
}