#include<bits/stdc++.h>
using namespace std;
#define int long long
int n,m,D[2010][2010],R[2010][2010],f[2010][2010],g[2010][2010];
const int mod=1e9+7;
signed main(){
	cin>>n>>m;
	if(n==1 && m==1){
		cout<<1;
		return 0;
	}
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			char c; cin>>c;
			if(c=='R') D[i][j]=R[i][j]=1;
		}
	}
	for(int i=n;i>=1;i--){
		for(int j=m;j>=1;j--){
			D[i][j]+=D[i+1][j];
			R[i][j]+=R[i][j+1];
		}
	}
	f[1][1]=g[1][1]=1;
	f[2][1]=g[1][2]=mod-1;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=m;j++){
			f[i][j]=(f[i][j]+f[i-1][j]+g[i-1][j])%mod;
			g[i][m-R[i][j+1]+1]=(g[i][m-R[i][j+1]+1]-f[i][j]+mod)%mod;
			g[i][j]=(g[i][j]+g[i][j-1]+f[i][j-1])%mod;
			f[n-D[i+1][j]+1][j]=(f[n-D[i+1][j]+1][j]-g[i][j]+mod)%mod;
		}
	}
	cout<<(f[n][m]+g[n][m])%mod;
	return 0;
}