#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <complex>
#define REP(i, n) for (int i = 0; i < (n); i++)

using namespace std;

const int MOD = 1e9 + 7;

struct mint {
    int n;
    mint(int n_ = 0) : n(n_) {}
};

mint operator+(mint a, mint b) { a.n += b.n; if (a.n >= MOD) a.n -= MOD; return a; }
mint operator-(mint a, mint b) { a.n -= b.n; if (a.n < 0) a.n += MOD; return a; }
mint operator*(mint a, mint b) { return (long long)a.n * b.n % MOD; }
mint &operator+=(mint &a, mint b) { return a = a + b; }
mint &operator-=(mint &a, mint b) { return a = a - b; }
mint &operator*=(mint &a, mint b) { return a = a * b; }

mint modpow(mint a, long long b) {
  mint res = 1;
  while (b > 0) {
    if (b & 1) res *= a;
    a *= a;
    b >>= 1;
  }
  return res;
}

mint F[200001] = {1, 1};
mint R[200001] = {1, 1};
mint I[200001] = {0, 1};

mint C(int n, int r) {
  if (n < 0 || r < 0 || n < r) return 0;
  return F[n] * R[n - r] * R[r];
}

void init() {
  for (int i = 2; i <= 200000; i++) {
    I[i] = I[MOD % i] * (MOD - MOD / i);
    F[i] = F[i - 1] * i;
    R[i] = R[i - 1] * I[i];
  }
}

int main() {
  init();
  int N, R;
  cin >> N >> R;
  vector<int> S(N);
  REP(i, N) cin >> S[i];
  sort(S.rbegin(), S.rend());
  int i = 0;
  vector<mint> A, B;
  while (i < N) {
    int j = i;
    while (i < N && S[i] == S[j]) i++;
    A.push_back(F[i - j] * C(i-j + j-1, i-j));
    B.push_back(F[i - j] * C(i-j-1 + j, j));
  }
  vector<mint> dp0(A.size() + 1);
  vector<mint> dp1(A.size() + 1);
  dp0[0] = R;
  for (int i = 0; i < A.size(); i++) {
    dp0[i+1] += dp0[i] * (A[i] + R*B[i]);
    dp1[i+1] += dp0[i] * B[i];
    dp1[i+1] += dp1[i] * (A[i] + R*B[i]);
  }
  cout << dp1[A.size()].n << '\n';
}