#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
#include<chrono>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 998244353;
//constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;

#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;

template<typename T>
void chmin(T& a, T b) {
	a = min(a, b);
}
template<typename T>
void chmax(T& a, T b) {
	a = max(a, b);
}
template<typename T>
void cinarray(vector<T>& v) {
	rep(i, v.size())cin >> v[i];
}
template<typename T>
void coutarray(vector<T>& v) {
	rep(i, v.size()) {
		if (i > 0)cout << " "; cout << v[i];
	}
	cout << "\n";
}
ll mod_pow(ll x, ll n, ll m = mod) {
	if (n < 0) {
		ll res = mod_pow(x, -n, m);
		return mod_pow(res, m - 2, m);
	}
	if (abs(x) >= m)x %= m;
	if (x < 0)x += m;
	//if (x == 0)return 0;
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
//mod should be <2^31
struct modint {
	int n;
	modint() :n(0) { ; }
	modint(ll m) {
		if (m < 0 || mod <= m) {
			m %= mod; if (m < 0)m += mod;
		}
		n = m;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
bool operator<(modint a, modint b) { return a.n < b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= (int)mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += (int)mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
modint operator/=(modint& a, modint b) { a = a / b; return a; }
const int max_n = 1 << 21;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}
modint combP(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[a - b];
}

ll gcd(ll a, ll b) {
	a = abs(a); b = abs(b);
	if (a < b)swap(a, b);
	while (b) {
		ll r = a % b; a = b; b = r;
	}
	return a;
}
using ld = long double;
//typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-10;
const ld pi = acosl(-1.0);
template<typename T>
void addv(vector<T>& v, int loc, T val) {
	if (loc >= v.size())v.resize(loc + 1, 0);
	v[loc] += val;
}
/*const int mn = 2000005;
bool isp[mn];
vector<int> ps;
void init() {
	fill(isp + 2, isp + mn, true);
	for (int i = 2; i < mn; i++) {
		if (!isp[i])continue;
		ps.push_back(i);
		for (int j = 2 * i; j < mn; j += i) {
			isp[j] = false;
		}
	}
}*/

//[,val)
template<typename T>
auto prev_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	if (res == st.begin())return st.end();
	res--; return res;
}

//[val,)
template<typename T>
auto next_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	return res;
}
using mP = pair<modint, modint>;
mP operator+(mP a, mP b) {
	return { a.first + b.first,a.second + b.second };
}
mP operator+=(mP& a, mP b) {
	a = a + b; return a;
}
mP operator-(mP a, mP b) {
	return { a.first - b.first,a.second - b.second };
}
mP operator-=(mP& a, mP b) {
	a = a - b; return a;
}
LP operator+(LP a, LP b) {
	return { a.first + b.first,a.second + b.second };
}
LP operator+=(LP& a, LP b) {
	a = a + b; return a;
}
LP operator-(LP a, LP b) {
	return { a.first - b.first,a.second - b.second };
}
LP operator-=(LP& a, LP b) {
	a = a - b; return a;
}

mt19937 mt(time(0));

const string drul = "DRUL";
string senw = "SENW";
//DRUL,or SENW
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
//-----------------------------------------



#define ftt function<T(T,T)>
#define ftu function<T(T,U,int,int)>
#define fuu function<U(U,U)>

template<typename T, typename U>
struct SegT {
private:
	int n;
	vector<T> node;
	vector<U> lazy;
	T et; U eu;
	ftt f;
	ftu g;
	fuu h;
public:
	SegT(vector<T> ori, T _et, U _eu, ftt _f, ftu _g, fuu _h) {
		int sz = ori.size();
		et = _et, eu = _eu; f = _f, g = _g, h = _h;
		n = 1;
		while (n < sz)n <<= 1;
		node.resize(2 * n - 1, et);
		lazy.resize(2 * n - 1, eu);
		rep(i, sz) {
			node[i + n - 1] = ori[i];
		}
		per(i, n - 1) {
			node[i] = f(node[2 * i + 1], node[2 * i + 2]);
		}
	}
	SegT(int sz, T _et, U _eu, ftt _f, ftu _g, fuu _h) {
		et = _et, eu = _eu; f = _f, g = _g, h = _h;
		n = 1;
		while (n < sz)n <<= 1;
		node.resize(2 * n - 1, et);
		lazy.resize(2 * n - 1, eu);
	}
	void eval(int k, int l, int r) {
		if (lazy[k] == eu)return;
		node[k] = g(node[k], lazy[k], l, r);
		if (r - l > 1) {
			lazy[2 * k + 1] = h(lazy[k], lazy[2 * k + 1]);
			lazy[2 * k + 2] = h(lazy[k], lazy[2 * k + 2]);
		}
		lazy[k] = eu;
	}
	void add(U x, int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0)r = n;
		eval(k, l, r);
		if (r <= a || b <= l)return;
		if (a <= l && r <= b) {
			lazy[k] = h(x, lazy[k]);
			eval(k, l, r);
		}
		else {
			add(x, a, b, k * 2 + 1, l, (l + r) / 2);
			add(x, a, b, k * 2 + 2, (l + r) / 2, r);
			node[k] = f(node[k * 2 + 1], node[k * 2 + 2]);
		}
	}
	T query(int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0)r = n;
		eval(k, l, r);
		if (r <= a || b <= l)return et;
		if (a <= l && r <= b)return node[k];
		else {
			T vl = query(a, b, k * 2 + 1, l, (l + r) / 2);
			T vr = query(a, b, k * 2 + 2, (l + r) / 2, r);
			return f(vl, vr);
		}
	}
	void update(int loc, T x) {
		int k = 0, l = 0, r = n;
		stack<P> st;
		while (k < n - 1) {
			eval(k, l, r);
			st.push({ l,r });
			if (loc < (l + r) / 2) {
				k = 2 * k + 1;
				r = (l + r) / 2;
			}
			else {
				k = 2 * k + 2;
				l = (l + r) / 2;
			}
		}
		eval(k, l, r);
		st.push({ l,r });
		node[k] = x;
		while (k > 0) {
			k = (k - 1) / 2;
			st.pop();
			l = st.top().first, r = st.top().second;
			eval(2 * k + 1, l, (l + r) / 2);
			eval(2 * k + 2, (l + r) / 2, r);
			node[k] = f(node[2 * k + 1], node[2 * k + 2]);
		}
	}
	//k以上でf(x,node[y+sz-1])をtrueにするような最小のy
	int searchloc(int le, T x, function<bool(T, T)> comp) {
		int k = 0, l = 0, r = n;
		while (k < n - 1) {
			eval(k, l, r);
			int m = (l + r) / 2;
			if (le < m) {
				k = 2 * k + 1; r = m;
			}
			else {
				k = 2 * k + 2; l = m;
			}
		}
		assert(k == le + n - 1);
		eval(k, l, r);
		if (comp(x, node[k]))return le;
		//x=f(x,node[k]);
		while (k > 0) {
			int mem = k;
			k = (k - 1) / 2;
			if (2 * k + 1 == mem) {
				r += r - l;
			}
			else {
				l -= r - l;
			}
			if (2 * k + 1 == mem) {
				eval(2 * k + 2, (l + r) / 2, r);
				if (comp(x, node[2 * k + 2])) {
					k = 2 * k + 2;
					l = (l + r) / 2;
					break;
				}
				//x=f(x,node[2*k+2]);
			}
		}
		if (k == 0)return n;
		while (k < n - 1) {
			eval(2 * k + 1, l, (l + r) / 2);
			eval(2 * k + 2, (l + r) / 2, r);
			if (comp(x, node[2 * k + 1])) {
				k = 2 * k + 1;
				r = (l + r) / 2;
			}
			else {
				k = 2 * k + 2;
				l = (l + r) / 2;
				//x=f(x,node[2*k+1]);
			}
		}
		return k - (n - 1);
	}
};

template<typename T>
struct BIT {
private:
	vector<T> node; int n;
public:
	BIT(int n_) {
		n = n_; node.resize(n, 0);
	}
	//0-indexed
	void add(int a, T w) {
		for (int i = a; i < n; i |= i + 1)node[i] += w;
	}
	//[0,a)
	T sum(int a) {
		T ret = 0;
		for (int i = a - 1; i >= 0; i = (i & (i + 1)) - 1)ret += node[i];
		return ret;
	}
	//[a,b)
	T sum(int a, int b) {
		return sum(b) - sum(a);
	}
};

ll calc(vector<P> vp) {
	vector<int> v0, v1;
	rep(i, vp.size()) {
		if (vp[i].second == 0)v0.push_back(vp[i].first);
		else v1.push_back(vp[i].first);
	}
	sort(all(v0));
	sort(all(v1));
	if (v0.size() > v1.size())return -1;
	vector<int> bel(v0.size());
	rep(i, v0.size())bel[i] = lower_bound(all(v1), v0[i]) - v1.begin();
	set<int> rst;
	rst.insert(-1);
	rep(i, v1.size())rst.insert(i);
	int ri = -1;

	BIT<ll> bt1(v1.size());

	using speP = pair<int, LP>;
	auto f = [&](speP a, speP b)->speP {
		if (a.first < b.first)return a;
		else if (a.first > b.first)return b;
		return { a.first,{a.second.first + b.second.first,a.second.second} };
	};
	auto g = [&](speP a, int b, int l, int r) {
		a.first -= b;
		return a;
	};
	auto h = [&](int a, int b) {
		return a + b;
	};
	SegT<speP, int> st(v0.size(), { mod,{INF,-1} }, 0, f, g, h);
	rep(i, v0.size()) {
		int loc = lower_bound(all(v1), v0[i]) - v1.begin();
		int to;
		if (loc == v1.size())to = loc - 1;
		else {
			to = loc;
			if (loc > 0 && v0[i] - v1[loc - 1] < v1[loc] - v0[i]) {
				to = loc - 1;
			}
		}
		if (to > ri) {
			//(i,to)
			rst.erase(to);
			ri = to;
			if (v0[i] <= v1[to]&&to>0) {
				ll ad = abs(v0[i] - v1[to - 1]);
				st.update(i, { to - bel[i],{2 * ad,i} });
			}
		}
		else {
			ll vl, vr;
			if (ri + 1 == v1.size())vr = INF;
			else {
				vr = abs(v0[i] - v1[to]);
			}
			auto itr = prev_itr(rst, ri);
			if ((*itr) == -1) {
				vl = INF;
			}
			else {
				int idr = i;
				int idl = i - (ri - (*itr));
				//[idl,idr)
				int le = *itr;
				vl = 0;
				if (v0[i - 1] <= ri) {
					vl -= v1[ri];
				}
				else {
					vl += v1[ri];
				}
				vl += abs(v0[i] - v1[ri]);
				if (v0[idl] <= v1[le + 1]) {
					vl += v1[le];
				}
				else {
					vl -= v1[le];
				}
				speP p = st.query(idl, idr);
				if (p.first == 0)vl += p.second.first;
			}
			if (vl > vr) {
				to = ri + 1;
				rst.erase(to);
				ri = to;
				if (v0[i] <= v1[to] && to > 0) {
					ll ad = abs(v0[i] - v1[to - 1]);
					st.update(i, { to - bel[i],{2 * ad,i} });
				}
			}
			else {
				int idr = i;
				int idl = i - (ri - (*itr));
				//[idl,idr)
				int le = *itr;
				rst.erase(le);
				st.add(1, idl, idr);
				while (true) {
					speP p = st.query(idl, idr);
					if (p.first < 0) {
						st.update(p.second.second, { mod,{INF,-1} });
					}
					else break;
				}
			}
		}
	}
	int cur = 0;
	ll res = 0;
	rep(i, v1.size())if (!rst.count(i)) {
		res += abs(v0[cur] - v1[i]);
		cur++;
	}
	return res;
}
void solve() {
	int n, m, k; cin >> n >> m >> k;
	vector<int> b(n);
	rep(i, n)cin >> b[i];
	vector<int> r(m);
	rep(i, m)cin >> r[i];
	if (n > m) {
		swap(n, m);
		swap(b, r);
	}
	vector<pair<int, P>> vp;
	rep(i, n) {
		vp.push_back({ b[i] % k,{b[i] / k,0} });
	}
	rep(i, m) {
		vp.push_back({ r[i] % k,{r[i] / k,1} });
	}
	sort(all(vp));
	ll ans = 0;
	rep(i, vp.size()) {
		vector<P> cur;
		cur.push_back(vp[i].second);
		while (i + 1 < vp.size() && vp[i].first == vp[i + 1].first) {
			i++; cur.push_back(vp[i].second);
		}
		ll val = calc(cur);
		if (val < 0) {
			cout << -1 << "\n"; return;
		}
		ans += val;
	}
	cout << ans << "\n";
}


signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(10);
	//init_f();
	//init();
	//expr();
	//while(true)
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}