#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define ull unsigned long long
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

#define mod 1000000007
struct modint{
	int x;
	modint(int o=0){x=o;}
	modint &operator = (int o){return x=o,*this;}
	modint &operator +=(modint o){return x=x+o.x>=mod?x+o.x-mod:x+o.x,*this;}
	modint &operator -=(modint o){return x=x-o.x<0?x-o.x+mod:x-o.x,*this;}
	modint &operator *=(modint o){return x=1ll*x*o.x%mod,*this;}
	modint &operator ^=(int b){
		modint a=*this,c=1;
		for(;b;b>>=1,a*=a)if(b&1)c*=a;
		return x=c.x,*this;
	}
	modint &operator /=(modint o){return *this *=o^=mod-2;}
	friend modint operator +(modint a,modint b){return a+=b;}
	friend modint operator -(modint a,modint b){return a-=b;}
	friend modint operator *(modint a,modint b){return a*=b;}
	friend modint operator /(modint a,modint b){return a/=b;}
	friend modint operator ^(modint a,int b){return a^=b;}
	friend bool operator ==(modint a,int b){return a.x==b;}
	friend bool operator !=(modint a,int b){return a.x!=b;}
	bool operator ! () {return !x;}
	modint operator - () {return x?mod-x:0;}
	bool operator <(const modint&b)const{return x<b.x;}
};
inline modint qpow(modint x,int y){return x^y;}

vector<modint> fac,ifac,iv;
inline void initC(int n)
{
	if(iv.empty())fac=ifac=iv=vector<modint>(2,1);
	int m=iv.size(); ++n;
	if(m>=n)return;
	iv.resize(n),fac.resize(n),ifac.resize(n);
	For(i,m,n-1){
		iv[i]=iv[mod%i]*(mod-mod/i);
		fac[i]=fac[i-1]*i,ifac[i]=ifac[i-1]*iv[i];
	}
}
inline modint C(int n,int m){
	if(m<0||n<m)return 0;
	return initC(n),fac[n]*ifac[m]*ifac[n-m];
}
inline modint sign(int n){return (n&1)?(mod-1):(1);}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair 
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 200005
#define inf 0x3f3f3f3f

int n,m;
char str[21][maxn];
int cnt[1<<20],mxs;
modint f[1<<20][21],g[1<<20];

modint val[maxn];

signed main()
{
	n=read(),m=read();
	initC(n+5);
//	For(i,1,n){
//		For(j,1,i)
//			val[i]+=fac[i]*ifac[i-j];
//	}
	For(i,1,n)val[i]=val[i-1]+ifac[i-1];
	For(i,1,n)val[i]*=fac[i];
	For(i,0,m-1)cin>>(str[i]+1);
	For(i,1,n){
		int s=0;
		For(j,0,m-1)if(str[j][i]=='H')s|=(1<<j);
		++cnt[s];
	}
	g[0]=val[cnt[0]]+1;
	// 0,1 : 3*1,3*1
	//       1*1
	mxs=(1<<m);
	For(s,0,mxs-1){
		For(i,0,m-1)if(f[s][i].x){
			For(j,i+1,m-1)if(!(s>>j&1)){
				if(cnt[s|(1<<j)]) g[s|(1<<j)]+=f[s][i]*val[cnt[s|(1<<j)]];
				f[s|(1<<j)][j]+=f[s][i];
			}
		}
		if(g[s].x){
			For(j,0,m-1)if(!(s>>j&1)){
				f[s|(1<<j)][j]+=g[s];
				if(cnt[s|(1<<j)]) g[s|(1<<j)]+=g[s]*val[cnt[s|(1<<j)]];
			}
		}
	}
	modint res=0;
	For(i,0,mxs-1) res+=g[i];
	res-=1;
	cout<<res.x;
	return 0;
}