#include <bits/stdc++.h>

using LL = long long;

const int N = 2e5 + 7;

LL ans;
int n, m, k, cnt, ok;
std::vector<std::pair<int, int>> a[N * 2];
std::vector<int> b[N * 2];
std::map<int, int> mp;

void solve(const std::vector<std::pair<int, int>> &a) {
  int now = N, lo = N, hi = N;
  for(auto &&[x, y]: a) 
    if(y) {
      b[++now].push_back(x);
      hi = std::max(hi, now);
    }
    else {
      b[now--].push_back(x);
      lo = std::min(lo, now);
    }
  if(now < N)
    ok = 0;
  for(int i = lo; i <= hi; ++i) {
    if(~b[i].size() & 1) 
      for(int j = 1; j < b[i].size(); j += 2)
	ans += b[i][j] - b[i][j - 1];
    else {
      std::vector<int> t(b[i].size());
      for(int j = int(b[i].size()) - 3; j >= 0; j -= 2)
	t[j] = t[j + 2] + b[i][j + 2] - b[i][j + 1];
      LL sum = 0, val = t[0];
      for(int j = 2; j < b[i].size(); j += 2) {
	sum += b[i][j - 1] - b[i][j - 2];
	val = std::min(val, sum + t[j]);
      }
      ans += val;
    }
    b[i].resize(0);
  }
}

int main() {

  scanf("%d%d%d", &n, &m, &k);
  for(int i = 1, x; i <= n; ++i) {
    scanf("%d", &x);
    if(!mp.count(x % k))
      mp[x % k] = ++cnt;
    a[mp[x % k]].push_back({x / k, n >= m});
  }
  for(int i = 1, x; i <= m; ++i) {
    scanf("%d", &x);
    if(!mp.count(x % k))
      mp[x % k] = ++cnt;
    a[mp[x % k]].push_back({x / k, n < m});
  }

  ok = 1;
  for(auto &&[_, c]: mp) {
    std::sort(a[c].begin(), a[c].end());
    solve(a[c]);
  }

  printf("%lld\n", ok ? ans : -1LL);
  
  return 0;
}