#include <bits/stdc++.h>
#define REP_(i, a_, b_, a, b, ...) \
  for (int i = (a), END_##i = (b); i < END_##i; ++i)
#define REP(i, ...) REP_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__)
#define ALL(x) std::begin(x), std::end(x)
using i64 = long long;

template<typename T, typename U>
inline bool chmax(T &a, U b) {
  return a < b and ((a = std::move(b)), true);
}
template<typename T, typename U>
inline bool chmin(T &a, U b) {
  return a > b and ((a = std::move(b)), true);
}
template<typename T>
inline int ssize(const T &a) {
  return (int) std::size(a);
}

template<typename T>
std::istream &operator>>(std::istream &is, std::vector<T> &a) {
  for (auto &x : a) is >> x;
  return is;
}
template<typename T, typename U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &a) {
  return os << "(" << a.first << ", " << a.second << ")";
}
template<typename Container>
std::ostream &print_seq(const Container &a, std::string_view sep = " ",
                        std::string_view ends = "\n",
                        std::ostream &os = std::cout) {
  auto b = std::begin(a), e = std::end(a);
  for (auto it = std::begin(a); it != e; ++it) {
    if (it != b) os << sep;
    os << *it;
  }
  return os << ends;
}
template<typename T, typename = void>
struct is_iterable : std::false_type {};
template<typename T>
struct is_iterable<T, std::void_t<decltype(std::begin(std::declval<T>())),
                                  decltype(std::end(std::declval<T>()))>>
    : std::true_type {
};

template<typename T, typename = std::enable_if_t<
    is_iterable<T>::value &&
        !std::is_same<T, std::string_view>::value &&
        !std::is_same<T, std::string>::value>>
std::ostream &operator<<(std::ostream &os, const T &a) {
  return print_seq(a, ", ", "", (os << "{")) << "}";
}

void print() { std::cout << "\n"; }
template<class T>
void print(const T &x) {
  std::cout << x << "\n";
}
template<typename Head, typename... Tail>
void print(const Head &head, Tail... tail) {
  std::cout << head << " ";
  print(tail...);
}

void read_from_cin() {}
template<typename T, typename... Ts>
void read_from_cin(T &value, Ts &...args) {
  std::cin >> value;
  read_from_cin(args...);
}
#define INPUT(type, ...) \
  type __VA_ARGS__;      \
  read_from_cin(__VA_ARGS__)

#ifdef ENABLE_DEBUG
#include "debug_dump.hpp"
#else
#define DUMP(...)
#endif

using namespace std;

template<typename Monoid>
struct SegTree {
  using T = typename Monoid::T;

  int n_;                // number of valid leaves.
  int offset_;           // where leaves start
  std::vector<T> data_;  // data size: 2*offset_

  inline int size() const { return n_; }
  inline int offset() const { return offset_; }

  explicit SegTree(int n) : n_(n) {
    offset_ = 1;
    while (offset_ < n_) offset_ <<= 1;
    data_.assign(2 * offset_, Monoid::id());
  }

  explicit SegTree(const std::vector<T> &leaves) : n_(leaves.size()) {
    offset_ = 1;
    while (offset_ < n_) offset_ <<= 1;
    data_.assign(2 * offset_, Monoid::id());
    for (int i = 0; i < n_; ++i) {
      data_[offset_ + i] = leaves[i];
    }
    for (int i = offset_ - 1; i > 0; --i) {
      data_[i] = Monoid::op(data_[i * 2], data_[i * 2 + 1]);
    }
  }

  // Sets i-th value (0-indexed) to x.
  void set(int i, const T &x) {
    int k = offset_ + i;
    data_[k] = x;
    // Update its ancestors.
    while (k > 1) {
      k >>= 1;
      data_[k] = Monoid::op(data_[k * 2], data_[k * 2 + 1]);
    }
  }

  // Queries by [l,r) range (0-indexed, half-open interval).
  T fold(int l, int r) const {
    l = std::max(l, 0) + offset_;
    r = std::min(r, offset_) + offset_;
    T vleft = Monoid::id(), vright = Monoid::id();
    for (; l < r; l >>= 1, r >>= 1) {
      if (l & 1) vleft = Monoid::op(vleft, data_[l++]);
      if (r & 1) vright = Monoid::op(data_[--r], vright);
    }
    return Monoid::op(vleft, vright);
  }

  T fold_all() const { return data_[1]; }

  // Returns i-th value (0-indexed).
  T operator[](int i) const { return data_[offset_ + i]; }

  friend std::ostream &operator<<(std::ostream &os, const SegTree &st) {
    os << "[";
    for (int i = 0; i < st.size(); ++i) {
      if (i != 0) os << ", ";
      const auto &x = st[i];
      os << x;
    }
    return os << "]";
  }
};
struct SumOp {
  using T = unsigned;
  static T op(const T &x, const T &y) { return x + y; }
  static constexpr T id() { return 0; }
};

template<typename T>
struct Compressed {
  std::vector<T> values;

  explicit Compressed(std::vector<T> v) : values(v) {
    std::sort(values.begin(), values.end());
    values.erase(std::unique(values.begin(), values.end()), values.end());
  }

  int size() const { return values.size(); }

  int index(T x) const {
    return std::lower_bound(values.begin(), values.end(), x) - values.begin();
  }

  const T &value(int i) const { return values[i]; }
};

// Binary search.
// Returns the boundary argument which satisfies pred(x).
//
// Usage:
//   auto ok_bound = bisect(ok, ng, [&](i64 x) -> bool { return ...; });
template<class F>
i64 bisect(i64 true_x, i64 false_x, F pred) {
  static_assert(std::is_invocable_r_v<bool, F, i64>, "F must be: i64 -> bool");
  // To allow negative values, use floor_div() in the loop.
  assert(true_x >= -1 and false_x >= -1);
  using u64 = unsigned long long;

  while (std::abs(true_x - false_x) > 1) {
    i64 mid = ((u64) true_x + (u64) false_x) / 2;
    if (pred(mid)) {
      true_x = std::move(mid);
    } else {
      false_x = std::move(mid);
    }
  }
  return true_x;
}

auto solve() {
  INPUT(i64, n, K, P);
  vector<unsigned> A(n), B(n);
  cin >> A >> B;
  REP(i, n) {
      A[i] %= P;
      B[i] %= P;
  }
  auto bb = B;
  bb.push_back(0);
  bb.push_back((unsigned) P);
  Compressed<unsigned> cb(bb);
  vector<unsigned> fb(cb.size());
  for (auto x : B) {
    int j = cb.index(x);
    fb[j]++;
  }
  SegTree<SumOp> seg(fb);

  i64 ans = bisect(P, -1, [&](i64 x) {
    i64 count = 0;
    REP(i, n) {
      unsigned a = A[i];
      if (a <= x) {
        int b1 = x + 1 - a;
        int r = cb.index(b1);
        count += seg.fold(0, r);
        int b2 = P - a;
        int l = cb.index(b2);
        r = cb.index(P);
        count += seg.fold(l, r);
      } else {
        int b1 = P - a;
        int l = cb.index(b1);
        int r = cb.index(P - a + x + 1);
        count += seg.fold(l, r);
      }
    }
    return count >= K;
  });
  return ans;
}

int main() {
  ios_base::sync_with_stdio(false), cin.tie(nullptr);
  cout << std::fixed << std::setprecision(15);
  int t = 1;
  REP(test_case, t) {
    auto ans = solve();
    print(ans);
  }
}