#include <bits/stdc++.h>
using namespace std;
const int Maxn = 2e5 + 100;
long long n, m, d, t, g[Maxn], r, l, T, f, mid;
pair<long long, long long> cv[Maxn];
vector<pair<long long, long long> > vec;
bool valid(long long x) {
  t = 0;
  for (int i = 1; i <= m + 1; i++) {
    f = g[i] - g[i - 1];
    if (f > x) return false;
    t += min(f, x - f);
    f = max(1ll * 0, f - (x - f));
    t += 2 * f;
  }
  if (t <= T) return true;
  return false;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  cin >> n >> m >> d >> T;
  for (int i = 0, a, b; i < n; i++) {
    cin >> a >> b;
    cv[i] = make_pair(a, b);
  }
  for (int i = 1; i <= m; i++) cin >> g[i];
  g[m + 1] = d;
  sort(g + 1, g + m + 1);
  sort(cv, cv + n);
  for (int i = 0; i < n; i++) {
    if (vec.empty() || cv[i].second > vec.back().second)
      vec.push_back(make_pair(cv[i].first, cv[i].second));
  }
  r = (int)vec.size() - 1;
  while (r - l > 1) {
    mid = (r + l) / 2;
    if (valid(vec[mid].second))
      r = mid;
    else
      l = mid;
  }
  if (!valid(vec.back().second))
    cout << -1;
  else if (valid(vec[0].second))
    cout << vec[0].first;
  else
    cout << vec[r].first;
}
