#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <forward_list>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T, typename V>
void ndarray(vector<T>& vec, const V& val, int len) { vec.assign(len, val); }
template <typename T, typename V, typename... Args> void ndarray(vector<T>& vec, const V& val, int len, Args... args) { vec.resize(len), for_each(begin(vec), end(vec), [&](T& v) { ndarray(v, val, args...); }); }
template <typename T> bool chmax(T &m, const T q) { return m < q ? (m = q, true) : false; }
template <typename T> bool chmin(T &m, const T q) { return m > q ? (m = q, true) : false; }
const std::vector<std::pair<int, int>> grid_dxs{{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
int floor_lg(long long x) { return x <= 0 ? -1 : 63 - __builtin_clzll(x); }
template <class T1, class T2> T1 floor_div(T1 num, T2 den) { return (num > 0 ? num / den : -((-num + den - 1) / den)); }
template <class T1, class T2> std::pair<T1, T2> operator+(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first + r.first, l.second + r.second); }
template <class T1, class T2> std::pair<T1, T2> operator-(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first - r.first, l.second - r.second); }
template <class T> std::vector<T> sort_unique(std::vector<T> vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; }
template <class T> int arglb(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::lower_bound(v.begin(), v.end(), x)); }
template <class T> int argub(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::upper_bound(v.begin(), v.end(), x)); }
template <class IStream, class T> IStream &operator>>(IStream &is, std::vector<T> &vec) { for (auto &v : vec) is >> v; return is; }

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec);
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr);
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const pair<T, U> &pa);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa);
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp);
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp);
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl);

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr) { os << '['; for (auto v : arr) os << v << ','; os << ']'; return os; }
#if __cplusplus >= 201703L
template <class... T> std::istream &operator>>(std::istream &is, std::tuple<T...> &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; }
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl) { os << '('; std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os << ')'; }
#endif
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa) { return os << '(' << pa.first << ',' << pa.second << ')'; }
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
#ifdef HITONANODE_LOCAL
const string COLOR_RESET = "\033[0m", BRIGHT_GREEN = "\033[1;32m", BRIGHT_RED = "\033[1;31m", BRIGHT_CYAN = "\033[1;36m", NORMAL_CROSSED = "\033[0;9;37m", RED_BACKGROUND = "\033[1;41m", NORMAL_FAINT = "\033[0;2m";
#define dbg(x) std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl
#define dbgif(cond, x) ((cond) ? std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl : std::cerr)
#else
#define dbg(x) ((void)0)
#define dbgif(cond, x) ((void)0)
#endif


// Cost scaling
// https://people.orie.cornell.edu/dpw/orie633/
template <class Cap, class Cost, int SCALING = 1, int REFINEMENT_ITER = 20>
struct mcf_costscaling {
    mcf_costscaling() = default;
    mcf_costscaling(int n) : _n(n), to(n), b(n), p(n) {}

    int _n;
    std::vector<Cap> cap;
    std::vector<Cost> cost;
    std::vector<int> opposite;
    std::vector<std::vector<int>> to;
    std::vector<Cap> b;
    std::vector<Cost> p;

    int add_edge(int from_, int to_, Cap cap_, Cost cost_) {
        assert(0 <= from_ and from_ < _n);
        assert(0 <= to_ and to_ < _n);
        assert(0 <= cap_);
        cost_ *= (_n + 1);
        const int e = int(cap.size());
        to[from_].push_back(e);
        cap.push_back(cap_);
        cost.push_back(cost_);
        opposite.push_back(to_);

        to[to_].push_back(e + 1);
        cap.push_back(0);
        cost.push_back(-cost_);
        opposite.push_back(from_);
        return e / 2;
    }
    void add_supply(int v, Cap supply) { b[v] += supply; }
    void add_demand(int v, Cap demand) { add_supply(v, -demand); }

    template <typename RetCost = Cost> RetCost solve() {
        Cost eps = 1;
        std::vector<int> que;
        for (const auto c : cost) {
            while (eps <= -c) eps <<= SCALING;
        }
        for (; eps >>= SCALING;) {
            auto no_admissible_cycle = [&]() -> bool {
                for (int i = 0; i < _n; i++) {
                    if (b[i]) return false;
                }
                std::vector<Cost> pp = p;
                for (int iter = 0; iter < REFINEMENT_ITER; iter++) {
                    bool flg = false;
                    for (int e = 0; e < int(cap.size()); e++) {
                        if (!cap[e]) continue;
                        int i = opposite[e ^ 1], j = opposite[e];
                        if (pp[j] > pp[i] + cost[e] + eps)
                            pp[j] = pp[i] + cost[e] + eps, flg = true;
                    }
                    if (!flg) return p = pp, true;
                }
                return false;
            };
            if (no_admissible_cycle()) continue; // Refine

            for (int e = 0; e < int(cap.size()); e++) {
                const int i = opposite[e ^ 1], j = opposite[e];
                const Cost cp_ij = cost[e] + p[i] - p[j];
                if (cap[e] and cp_ij < 0)
                    b[i] -= cap[e], b[j] += cap[e], cap[e ^ 1] += cap[e], cap[e] = 0;
            }
            que.clear();
            int qh = 0;
            for (int i = 0; i < _n; i++) {
                if (b[i] > 0) que.push_back(i);
            }
            std::vector<int> iters(_n);
            while (qh < int(que.size())) {
                const int i = que[qh++];
                for (; iters[i] < int(to[i].size()) and b[i]; ++iters[i]) { // Push
                    int e = to[i][iters[i]];
                    if (!cap[e]) continue;
                    int j = opposite[e];
                    Cost cp_ij = cost[e] + p[i] - p[j];
                    if (cp_ij >= 0) continue;
                    Cap f = b[i] > cap[e] ? cap[e] : b[i];
                    if (b[j] <= 0 and b[j] + f > 0) que.push_back(j);
                    b[i] -= f, b[j] += f, cap[e] -= f, cap[e ^ 1] += f;
                }

                if (b[i] > 0) { // Relabel
                    bool flg = false;
                    for (int e : to[i]) {
                        if (!cap[e]) continue;
                        Cost x = p[opposite[e]] - cost[e] - eps;
                        if (!flg or x > p[i]) flg = true, p[i] = x;
                    }
                    que.push_back(i), iters[i] = 0;
                }
            }
        }
        RetCost ret = 0;
        for (int e = 0; e < int(cap.size()); e += 2) ret += RetCost(cost[e]) * cap[e ^ 1];
        return ret / (_n + 1);
    }
    std::vector<Cost> potential() const {
        std::vector<Cost> ret = p, c0 = cost;
        for (auto &x : ret) x /= (_n + 1);
        for (auto &x : c0) x /= (_n + 1);
        while (true) {
            bool flg = false;
            for (int i = 0; i < _n; i++) {
                for (const auto e : to[i]) {
                    if (!cap[e]) continue;
                    int j = opposite[e];
                    auto y = ret[i] + c0[e];
                    if (ret[j] > y) ret[j] = y, flg = true;
                }
            }
            if (!flg) break;
        }
        return ret;
    }
    struct edge {
        int from, to;
        Cap cap, flow;
        Cost cost;
    };
    edge get_edge(int e) const {
        int m = cap.size() / 2;
        assert(e >= 0 and e < m);
        return {opposite[e * 2 + 1], opposite[e * 2], cap[e * 2] + cap[e * 2 + 1], cap[e * 2 + 1],
                cost[e * 2] / (_n + 1)};
    }
    std::vector<edge> edges() const {
        int m = cap.size() / 2;
        std::vector<edge> result(m);
        for (int i = 0; i < m; i++) result[i] = get_edge(i);
        return result;
    }
};



int main() {
    int N, M, K;
    cin >> N >> M >> K;
    vector<int> A(N), B(M);
    cin >> A >> B;

    map<int, vector<pint>> mp;
    REP(i, N) {
        mp[A.at(i) % K].emplace_back(A.at(i) / K, 0);
    }
    REP(j, M) {
        mp[B.at(j) % K].emplace_back(B.at(j) / K, 1);
    }

    lint ret = 0;
    int nmatch = 0;
    for (auto [key, vs] : mp) {
        sort(ALL(vs));
        dbg(vs);
        int n0 = 0, n1 = 0;
        for (auto [x, t] : vs) {
            (t ? n1 : n0)++;
        }
        nmatch += min(n0, n1);

        if (n0 > n1) {
            swap(n0, n1);
            for (auto &[x, t] : vs) t ^= 1;
        }

        mcf_costscaling<int, lint> graph(vs.size() + 1);
        graph.add_supply(vs.size(), -n0);
        REP(i, vs.size()) {
            auto [x, t] = vs.at(i);
            if (t == 0) {
                graph.add_supply(i, 1);
            } else {
                graph.add_edge(i, vs.size(), 1, 0);
            }
        }
        FOR(i, 1, vs.size()) {
            int dx = vs.at(i).first - vs.at(i - 1).first;
            graph.add_edge(i - 1, i, n0, dx);
            graph.add_edge(i, i - 1, n0, dx);
        }

        ret += graph.solve();

        assert(n0 <= n1);
    }

    if (nmatch < min(N, M)) ret = -1;

    cout << ret << endl;
}