#pragma GCC optimize("O3")
#include <bits/stdc++.h>

using namespace std;

#define pc(x) __builtin_popcount(x)
#define rep(i, s, e) for (int i = s; i <= e; ++i)
#define drep(i, s, e) for (int i = s; i >= e; --i)
#define file(a) freopen(#a".in", "r", stdin), freopen(#a".out", "w", stdout)
#define pv(a) cout << #a << " = " << a << endl
#define pa(a, l, r) cout << #a " : "; rep(_, l, r) cout << a[_] << ' '; cout << endl

const int P = 1e9 + 7;

const int N = 1 << 20;
const int M = 20 + 5;

int read() {
  int x = 0, f = 1; char c = getchar();
  for (; c < '0' || c > '9'; c = getchar()) if (c == '-') f = -1;
  for (; c >= '0' && c <= '9'; c = getchar()) x = x * 10 + c - 48;
  return x * f;
}

int inc(int a, int b) { return (a += b) >= P ? a - P : a; }
int dec(int a, int b) { return (a -= b) < 0 ? a + P : a; }
int mul(int a, int b) { return 1ll * a * b % P; }
int qpow(int a, int b) { int res = 1; for (; b; b >>= 1, a = mul(a, a)) if (b & 1) res = mul(res, a); return res; }

int n, m, a[N], cnt[N], coef[N], C[M][M], f[N], ans;
char s[N];

int main() {
  n = read(), m = read();
  rep(d, 0, m - 1) {
    scanf("%s", s + 1);
    rep(i, 1, n) a[i] |= (s[i] == 'H') << d;
  }
  rep(i, 1, n) {
    ++ cnt[a[i]], coef[i] = mul(inc(coef[i - 1], 1), i);
  }
  rep(i, 0, m) C[i][0] = 1;
  rep(i, 1, m) rep(j, 1, i) C[i][j] = inc(C[i - 1][j], C[i - 1][j - 1]);
  for (int s = 0; s < 1 << m; ++ s) {
    int x = s >> 10, y = s & 0x3ff, val = 1;
    for (int t = x; ; t = x & (t - 1)) {
      val = inc(val, f[(t << 10) | y]);
      if (!t) break;
    }
    val = mul(val, coef[cnt[s]]);
    for (int t = y; t < 1 << 10; t = y | (t + 1)) {
      f[(x << 10) | t] = inc(f[(x << 10) | t], val);
    }
  }
  for (int x = 0; x < 1 << 10; ++ x) ans = inc(ans, f[(x << 10) | 0x3ff]);
  printf("%d\n", ans);
  return 0;
}