#include <bits/stdc++.h>
using namespace std;
inline char read() {
  static const int IN_LEN = 1000000;
  static char buf[IN_LEN], *s, *t;
  return (s == t               ? t = (s = buf) + fread(buf, 1, IN_LEN, stdin),
          (s == t ? -1 : *s++) : *s++);
}
template <class T>
inline void read(T &x) {
  static bool iosig;
  static char c;
  for (iosig = false, c = read(); !isdigit(c); c = read()) {
    if (c == '-') iosig = true;
    if (c == -1) return;
  }
  for (x = 0; isdigit(c); c = read()) x = ((x + (x << 2)) << 1) + (c ^ '0');
  if (iosig) x = -x;
}
const int OUT_LEN = 10000000;
char obuf[OUT_LEN], *ooh = obuf;
inline void print(char c) {
  if (ooh == obuf + OUT_LEN) fwrite(obuf, 1, OUT_LEN, stdout), ooh = obuf;
  *ooh++ = c;
}
template <class T>
inline void print(T x) {
  static int buf[30], cnt;
  if (x == 0)
    print('0');
  else {
    if (x < 0) print('-'), x = -x;
    for (cnt = 0; x; x /= 10) buf[++cnt] = x % 10 + 48;
    while (cnt) print((char)buf[cnt--]);
  }
}
inline void flush() { fwrite(obuf, 1, ooh - obuf, stdout); }
const int N = 100005;
int n, k, l, m, a[N];
bool vis[N];
long long ans;
int main() {
  read(n), read(k), read(l);
  m = n * k;
  for (register int i = (1); i <= (m); ++i) read(a[i]);
  sort(a + 1, a + m + 1);
  int j = 1;
  while (a[j + 1] - a[1] <= l && j <= m) ++j;
  if (j < n) return puts("0"), 0;
  int tot = n;
  for (register int i = (0); i < (n); ++i)
    if (i * k + 1 <= j && tot)
      vis[i * k + 1] = 1, --tot, ans += a[i * k + 1];
    else
      break;
  for (register int i = (j); i >= (1); --i)
    if (!vis[i] && tot) vis[i] = 1, --tot, ans += a[i];
  printf("%lld", ans);
  return 0;
}
