#include <bits/stdc++.h>
using namespace std;

#ifdef CKISEKI
#define safe cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
template <typename ...T>
void debug_(const char *s, T ...a) {
  cerr << "\e[1;32m(" << s << ") = (";
  int cnt = sizeof...(T);
  (..., (cerr << a << (--cnt ? ", " : ")\e[0m\n")));
}
template <typename I>
void orange_(const char *s, I L, I R) {
  cerr << "\e[1;32m[ " << s << " ] = [ ";
  for (int f = 0; L != R; ++L)
    cerr << (f++ ? ", " : "") << *L;
  cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) safe
#define orange(...) safe
#endif

const int mod = 1000000007;

int modpow(int64_t e, int p) {
  int64_t r = 1;
  while (p) {
    if (p & 1) r = r * e % mod;
    e = e * e % mod;
    p >>= 1;
  }
  return r;
}

const int maxn = 1005;
int g[maxn];

int gao(int i, int l, int r) {
  int64_t coef = 1, ans = 0;
  const int inv2 = (mod + 1) / 2;
  for (int j = l; j < r; j++) {
    ans = (ans + g[j - i + 1] * coef) % mod;
    coef = coef * inv2 % mod;
  }
  return ans;
}

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  for (int len = 0; len < maxn; len++) {
    g[len] = (2 * len * len * len + 3 * len * len + 3 * len + 3) % mod;
  }

  // for (int len = maxn - 1; len >= 0; len--) {
  for (int len = 1; len < maxn; len++) {
    for (int i = 1; i < len; i++) {
      g[len] = (g[len] - 1LL * (len - i + 1) * g[i] % mod + mod) % mod;
    }
  }

  int n, m;
  cin >> n >> m;
  vector<int> c(n);

  vector<int> cnt(m);
  for (int i = 0; i < n; i++) {
    cin >> c[i];
    --c[i];
    cnt[c[i]] += 1;
  }

  for (int j = 0; j < m; j++)
    if (cnt[j] == 0) {
      cout << 0 << '\n';
      return 0;
    }

  vector<int> p21(n + 1), p2(n + 1), invp21(n + 1);
  p2[0] = 1;
  p21[0] = 0;
  for (int i = 1; i <= n; i++) {
    p2[i] = (p2[i-1] + p2[i-1]) % mod;
    p21[i] = (p21[i-1] + p21[i-1] + 1) % mod;
  }

  for (int i = 1; i <= n; i++) {
    invp21[i] = modpow(p21[i], mod - 2);
  }

  int64_t ans = 0;

  vector<int> pos(m, -1);
  for (int i = n - 1; i >= 0; i--) {
    pos[c[i]] = i;
    vector<int> evt;

    int64_t prod = 1;
    for (int j = 0; j < m; j++) {
      if (pos[j] != -1) {
        evt.push_back(pos[j]);
      }
      prod = prod * p21[cnt[c[i]]] % mod;
    }
    sort(evt.begin(), evt.end());
    int f = i;
    for (int p: evt) {
      // [f, p)
      if (f != p) {
        debug(i, f, p, prod * gao(i, f, p) % mod);
        ans = (ans + prod * gao(i, f, p)) % mod;
        f = p;
      }
      prod = prod * invp21[cnt[c[i]]] % mod;
      prod = prod * p2[cnt[c[i]]] % mod;
    }

    debug(i, f, n, prod * gao(i, f, n) % mod);
    ans = (ans + prod * gao(i, f, n)) % mod;
  }

  cout << ans << '\n';
}