#include <bits/stdc++.h>
using namespace std;
const int NMAX = 400000 + 5;
int n, k, s, t;
int g[NMAX];
vector<pair<int, int> > cars;
bool works(int cap) {
  long long int tmp = 0;
  for (int i = 2; i <= k; ++i) {
    long long int dst = g[i] - g[i - 1];
    if (cap < dst) return false;
    if (cap >= 2 * dst)
      tmp += dst;
    else
      tmp += (dst * 2LL - (cap - dst));
  }
  return tmp <= t;
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  cars.resize(n + 1);
  for (int i = 1; i <= n; ++i) cin >> cars[i].second >> cars[i].first;
  sort(cars.begin() + 1, cars.end());
  for (int i = 2; i <= k + 1; ++i) cin >> g[i];
  g[k + 2] = s;
  k += 2;
  sort(g + 1, g + k + 1);
  int st = 1;
  int dr = n;
  int ans = n + 1;
  int mid;
  while (st <= dr) {
    mid = (st + dr) >> 1;
    if (works(cars[mid].first)) {
      ans = mid;
      dr = mid - 1;
    } else
      st = mid + 1;
  }
  if (ans == n + 1) {
    cout << "-1\n";
    return 0;
  }
  int yay = cars[ans].second;
  for (int i = ans + 1; i <= n; ++i) yay = min(yay, cars[i].second);
  cout << yay << '\n';
  return 0;
}
