#include <bits/stdc++.h>    

using namespace std;

typedef long long ll;

const int N = (int)(1 << 20) + 12, MOD = (int)1e9 + 7;

ll f[N], f1[N], p[N];
int n, m;
ll dp[N], c[N];
string s[N];
vector<vector<int>> cur;
ll binpow(ll a, ll b) {
    ll ret = 1, k = a;
    while(b) {
        if(b & 1) {
            ret *= k;
            ret %= MOD;
        }
        k *= k;
        k %= MOD;
        b /= 2;
    }
    return ret;
}
void prec() {
    f1[0] = f[0] = 1;
    p[0] = 1;
    for(int i = 1; i <= n; i++) {
        f[i] = f[i - 1] * 1ll * i % MOD;
        f1[i] = binpow(f[i], MOD - 2);
        p[i] = p[i - 1] + f1[i];
        if(p[i] >= MOD) p[i] -= MOD;
    }
}
ll calc(ll s) {
    ll ret = f[s] * p[s] % MOD;
    ret--;
    if(ret < 0) ret += MOD;
    return ret;
}
void test() {
    cin >> n >> m;
    prec();
    for(int i = 0; i < m; i++) {
        cin >> s[i];
    }

    for(int i = 0; i < n; i++) {
        int f = 0;
        for(int j = 0; j < m; j++) {
            if(s[j][i] == 'H') {
                f += (1 << j);
            }
        }
        c[f]++;
    }
    for(int i = (1 << m) - 1; i >= 0; i--) {
        dp[i] = calc(c[i]);
        for(int j = i + 1; j < (1 << m); j++) {
            if(j & i == i) {
                dp[i] += dp[j] * calc(c[i]) % MOD;
                dp[i] %= MOD;
            }
        }
    }
    ll res = 0;
    for(int i = 0; i < (1 << m); i++) {
        res += dp[i];
        if(res >= MOD) res -= MOD;
    }
    cout << res << '\n';
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    int t = 1;
    // cin >> t;
    
    while(t--)
        test();
}