#include <bits/stdc++.h>
using namespace std;
long long b[1510100], n, x;
long long Mod, C;
long long power(long long a, long long n, long long mod) {
  if (n == 0) return 1;
  long long y;
  y = power(a, n / 2, mod);
  if (n & 1) {
    return (((y * y) % mod) * a) % mod;
  } else {
    return (y * y) % mod;
  }
}
bool func(int mid) {
  int i, j, k;
  long long EX, sum;
  EX = power(x, mid, Mod);
  sum = 0;
  for (i = 0; i < n; i++) {
    if (b[i] >= mid)
      break;
    else {
      sum += power(x, b[i], EX);
      sum %= EX;
    }
  }
  if (sum == 0)
    return true;
  else
    return false;
}
int main() {
  int i, j, k;
  scanf("%d", &n);
  scanf("%d", &x);
  long long mx, quan;
  mx = 0;
  quan = 0;
  int a[n];
  for (i = 0; i < n; i++) {
    scanf("%d", &a[i]);
    mx = max(mx, (long long)a[i]);
    quan += a[i];
  }
  quan = quan - mx;
  for (i = 0; i < n; i++) {
    b[i] = mx - a[i];
  }
  sort(b, b + n);
  int hi, lo, mid;
  hi = mx;
  lo = 0;
  Mod = 1000000007;
  while (hi != lo) {
    mid = (hi + lo + 1) / 2;
    if (func(mid)) {
      lo = mid;
    } else {
      hi = mid - 1;
    }
  }
  quan += hi;
  cout << power(x, quan, Mod);
}
