#include <bits/stdc++.h>
using namespace std;
template <class T>
inline bool rd(T &num) {
  char in;
  bool IsN = false;
  while (in = getchar(), in != '-' && (in < '0' || in > '9'))
    if (in == EOF) return false;
  in == '-' ? (IsN = true, num = 0) : num = in - '0';
  while (in = getchar(), in >= '0' && in <= '9') num = num * 10 + in - '0';
  return IsN ? num = -num : num, true;
}
string nico;
const int maxn = 2e5 + 7;
const int inf = 2e9 + 7;
const int mod = 1e9 + 7;
int len[maxn];
int main() {
  ios::sync_with_stdio(false);
  long long n, k, x;
  cin >> n >> k >> x;
  for (register int i = (0); i < (n * k); i++) cin >> len[i];
  sort(len, len + n * k);
  int l = 0, r = 0;
  for (register int i = (0); i < (n * k); i++) {
    if (len[i] - len[0] <= x) r = i;
  };
  ;
  ;
  ;
  if (r + 1 < n) {
    cout << 0 << endl;
    return 0;
  }
  long long ans = 0;
  int cnt = 0;
  int have = n * k - r - 1;
  while (have) {
    cnt++;
    ans += len[r];
    have -= k - 1;
    if (have < 0) {
      ans -= len[r];
      r -= abs(have);
      have = 0;
      ans += len[r];
    }
    r--;
  }
  while (cnt != n) {
    cnt++;
    ans += len[r - k + 1];
    r -= k;
  }
  cout << ans << endl;
  return 0;
}
