#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

namespace {

Int op(Int x, Int y) { return std::max(x, y); }
Int e() { return -inf(); }

void solve() {
  Int n, A, B;
  scan(n, A, B);
  Vec<Int> a(2 * n);
  scan(a);
  ranges::sort(a);

  Int base = 0;
  for (i : rep(n)) {
    if (a[2 * i] + A < a[2 * i + 1]) {
      print(-1);
      return;
    }
    base += a[2 * i + 1] <= a[2 * i] + B;
  }

  Vec<Int> suff(n + 1);
  for (i : rev(rep(n))) {
    suff[i] = suff[i + 1];
    if (i) {
      suff[i] += a[2 * i] <= a[2 * i - 1] + B;
      suff[i] -= a[2 * i + 1] <= a[2 * i] + B;
    }
  }

  atcoder::segtree<Int, op, e> seg(n);

  Vec<Int> f(n + 1);
  for (l : rev(rep(n))) {
    f[l] = f[l + 1];
    Int cur = 0;
    cur -= a[2 * l + 1] <= a[2 * l] + B;
    Int ok = l;
    Int ng = n;
    while (ok + 1 < ng) {
      Int mid = std::midpoint(ok, ng);
      (a[2 * mid] + A < a[2 * mid + 1] ? ng : ok) = mid;
    }
    seg.set(l, f[l + 1] - suff[l + 1]);
    chmax(f[l], cur + suff[l + 1] + seg.prod(l + 1, ng));
  }

  print(base + f[0]);
}

}  // namespace

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  std::cout << std::setprecision(std::numeric_limits<Float>::max_digits10);

  Int t;
  scan(t);
  while (t--) {
    solve();
  }
}

#else  // __INCLUDE_LEVEL__

#include <bits/stdc++.h>

namespace atcoder {

namespace internal {

using std::bit_ceil;

int countr_zero(unsigned int n) { return __builtin_ctz(n); }

constexpr int countr_zero_constexpr(unsigned int n) {
  int x = 0;
  while (!(n & (1 << x))) x++;
  return x;
}

}  // namespace internal

}  // namespace atcoder

namespace atcoder {

template <class S, auto op, auto e>
struct segtree {
  static_assert(std::is_convertible_v<decltype(op), std::function<S(S, S)>>,
                "op must work as S(S, S)");
  static_assert(std::is_convertible_v<decltype(e), std::function<S()>>,
                "e must work as S()");

 public:
  segtree() : segtree(0) {}
  explicit segtree(int n) : segtree(std::vector<S>(n, e())) {}
  explicit segtree(const std::vector<S>& v) : _n(int(v.size())) {
    size = (int)internal::bit_ceil((unsigned int)(_n));
    log = internal::countr_zero((unsigned int)size);
    d = std::vector<S>(2 * size, e());
    for (int i = 0; i < _n; i++) d[size + i] = v[i];
    for (int i = size - 1; i >= 1; i--) {
      update(i);
    }
  }

  void set(int p, S x) {
    assert(0 <= p && p < _n);
    p += size;
    d[p] = x;
    for (int i = 1; i <= log; i++) update(p >> i);
  }

  S get(int p) const {
    assert(0 <= p && p < _n);
    return d[p + size];
  }

  S prod(int l, int r) const {
    assert(0 <= l && l <= r && r <= _n);
    S sml = e(), smr = e();
    l += size;
    r += size;

    while (l < r) {
      if (l & 1) sml = op(sml, d[l++]);
      if (r & 1) smr = op(d[--r], smr);
      l >>= 1;
      r >>= 1;
    }
    return op(sml, smr);
  }

  S all_prod() const { return d[1]; }

  template <bool (*f)(S)>
  int max_right(int l) const {
    return max_right(l, [](S x) { return f(x); });
  }
  template <class F>
  int max_right(int l, F f) const {
    assert(0 <= l && l <= _n);
    assert(f(e()));
    if (l == _n) return _n;
    l += size;
    S sm = e();
    do {
      while (l % 2 == 0) l >>= 1;
      if (!f(op(sm, d[l]))) {
        while (l < size) {
          l = (2 * l);
          if (f(op(sm, d[l]))) {
            sm = op(sm, d[l]);
            l++;
          }
        }
        return l - size;
      }
      sm = op(sm, d[l]);
      l++;
    } while ((l & -l) != l);
    return _n;
  }

  template <bool (*f)(S)>
  int min_left(int r) const {
    return min_left(r, [](S x) { return f(x); });
  }
  template <class F>
  int min_left(int r, F f) const {
    assert(0 <= r && r <= _n);
    assert(f(e()));
    if (r == 0) return 0;
    r += size;
    S sm = e();
    do {
      r--;
      while (r > 1 && (r % 2)) r >>= 1;
      if (!f(op(d[r], sm))) {
        while (r < size) {
          r = (2 * r + 1);
          if (f(op(d[r], sm))) {
            sm = op(d[r], sm);
            r--;
          }
        }
        return r + 1 - size;
      }
      sm = op(d[r], sm);
    } while ((r & -r) != r);
    return 0;
  }

 private:
  int _n, size, log;
  std::vector<S> d;

  void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};

}  // namespace atcoder

using Int = int64_t;
using Float = double;
using Str = std::string;

template <class T1, class T2>
using Pair = std::pair<T1, T2>;

template <class... Ts>
using Tuple = std::tuple<Ts...>;

template <class T, size_t N>
using Arr = std::array<T, N>;

template <class T>
using Vec = std::vector<T>;

template <class T>
using Set = std::set<T>;

template <class T>
using Multiset = std::multiset<T>;

template <class K, class T>
using Map = std::map<K, T>;

template <class T>
using MinHeap = std::priority_queue<T, Vec<T>, std::greater<T>>;

template <class T>
using MaxHeap = std::priority_queue<T>;

namespace ranges = std::ranges;
namespace views = std::views;

inline constexpr auto len = ranges::ssize;
inline constexpr auto rev = views::reverse;

constexpr auto rep(Int l, Int r) { return views::iota(std::min(l, r), r); }
constexpr auto rep(Int n) { return rep(0, n); }
constexpr auto rep1(Int l, Int r) { return rep(l, r + 1); }
constexpr auto rep1(Int n) { return rep(1, n + 1); }

template <class T, class U = T>
bool chmin(T& x, U&& y) {
  return y < x && (x = std::forward<U>(y), true);
}

template <class T, class U = T>
bool chmax(T& x, U&& y) {
  return x < y && (x = std::forward<U>(y), true);
}

template <std::signed_integral T = Int>
T inf() {
  T ret;
  std::memset(&ret, 0x3f, sizeof(ret));
  return ret;
}

template <std::floating_point T>
T inf() {
  return std::numeric_limits<T>::infinity();
}

template <class T>
concept Range = ranges::range<T> && !std::convertible_to<T, std::string_view>;

template <class T>
concept TupleLike = std::__is_tuple_like<T>::value && !Range<T>;

namespace std {

istream& operator>>(istream& is, Range auto&& r) {
  for (auto&& e : r) {
    is >> e;
  }
  return is;
}

istream& operator>>(istream& is, TupleLike auto&& t) {
  return apply([&](auto&... xs) -> istream& { return (is >> ... >> xs); }, t);
}

ostream& operator<<(ostream& os, Range auto&& r) {
  for (string_view sep = ""; auto&& e : r) {
    os << exchange(sep, " ") << e;
  }
  return os;
}

ostream& operator<<(ostream& os, TupleLike auto&& t) {
  const auto f = [&](auto&... xs) -> ostream& {
    [[maybe_unused]] string_view sep = "";
    ((os << exchange(sep, " ") << xs), ...);
    return os;
  };
  return apply(f, t);
}

}  // namespace std

#define DEF_INC_OR_DEC(op) \
  auto& operator op(Range auto&& r) { \
    for (auto&& e : r) { \
      op e; \
    } \
    return r; \
  } \
  auto& operator op(TupleLike auto&& t) { \
    std::apply([](auto&... xs) { (op xs, ...); }, t); \
    return t; \
  }

DEF_INC_OR_DEC(++)
DEF_INC_OR_DEC(--)

#undef DEF_INC_OR_DEC

void scan(auto&&... xs) { std::cin >> std::tie(xs...); }
void print(auto&&... xs) { std::cout << std::tie(xs...) << '\n'; }

template <class F>
class fix {
 public:
  explicit fix(F f) : f_(std::move(f)) {}

  decltype(auto) operator()(auto&&... xs) const {
    return f_(std::ref(*this), std::forward<decltype(xs)>(xs)...);
  }

 private:
  F f_;
};

#define for(...) for ([[maybe_unused]] auto&& __VA_ARGS__)

#endif  // __INCLUDE_LEVEL__