#include <bits/stdc++.h>
using namespace std;
map<long long, long long> ais;
long long fastexpo(long long base, long long pw) {
  if (pw == 0) return 1ll;
  if (pw == 1) return base;
  long long res = fastexpo(base, pw / 2);
  res *= res;
  res %= 1000000007;
  if (pw % 2 == 1) res = (res * base) % 1000000007;
  return res;
}
int main() {
  long long n, x, ai;
  cin >> n >> x;
  long long tot = 0;
  map<long long, long long>::iterator it;
  for (int i = 0; i < n; ++i) {
    cin >> ai;
    tot += ai;
    ai *= -1ll;
    it = ais.find(ai);
    if (it == ais.end()) {
      ais[ai] = 1;
    } else {
      ++ais[ai];
    }
  }
  it = ais.begin();
  long long nitf, tmp;
  while (it != ais.end()) {
    nitf = -(it->first);
    if ((it->second) % x > 0 || (nitf < 0)) {
      cout << fastexpo(x, min(tot - nitf, tot));
      return 0;
    }
    tmp = (it->second) / x;
    (ais.find(-nitf + 1) != ais.end()) ? ais[-nitf + 1] += tmp
                                       : ais[-nitf + 1] = tmp;
    ++it;
  }
  return 0;
}
