#include <bits/stdc++.h>
using namespace std;
int n, k, s, t;
vector<pair<int, int> > vec;
vector<int> gas;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  cin >> n >> k >> s >> t;
  vec.resize(n);
  gas.resize(k + 1);
  gas[0] = 0;
  for (int i = 0; i < n; i++) cin >> vec[i].second >> vec[i].first;
  sort(vec.begin(), vec.end());
  for (int i = 1; i <= k; i++) cin >> gas[i];
  gas.push_back(s);
  sort(gas.begin(), gas.end());
  int s = 0, e = n - 1, ans = n + 1;
  while (s <= e) {
    int mid = (s + e) / 2;
    int tank = vec[mid].first, tim = 0;
    bool flag = 0;
    for (int i = 0; i < gas.size() - 1; i++) {
      int dis = gas[i + 1] - gas[i];
      if (tank < dis) {
        flag = 1;
        break;
      }
      if (dis * 2 <= tank) {
        tim += dis;
        if (tim > t) {
          flag = 1;
          break;
        }
        continue;
      }
      int z = tank - dis;
      tim += z;
      tim += 2 * (dis - z);
      if (tim > t) {
        flag = 1;
        break;
      }
    }
    if (flag)
      s = mid + 1;
    else
      e = mid - 1, ans = min(ans, mid);
  }
  if (ans == n + 1) return cout << -1, 0;
  int mi = 1e9;
  for (int i = ans; i < n; i++) {
    mi = min(mi, vec[i].second);
  }
  cout << mi;
  return 0;
}
