#include <bits/stdc++.h>
using namespace std;
int n, k, s, t;
vector<int> coor;
bool can(int w) {
  int tm = 0;
  if (coor[0] > w) return 0;
  int x = coor[0];
  tm += min(x, w - x);
  x -= min(x, w - x);
  tm += 2 * x;
  for (int i = 0; i < k; i++) {
    int x = coor[i + 1] - coor[i];
    if (x > w) return 0;
    tm += min(x, w - x);
    x -= min(x, w - x);
    tm += 2 * x;
  }
  if (tm > t) return 0;
  return 1;
}
int bin_search() {
  int l = -1, r = 1e9 + 1;
  while (r - l > 1) {
    int m = (r + l) / 2;
    if (can(m))
      r = m;
    else
      l = m;
  }
  return l;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > car(n);
  for (int i = 0; i < n; i++) cin >> car[i].first >> car[i].second;
  coor.resize(k);
  for (int i = 0; i < k; i++) cin >> coor[i];
  coor.push_back(s);
  sort(coor.begin(), coor.end());
  int w = bin_search();
  w++;
  int ans = 1e9 + 1;
  for (int i = 0; i < n; i++)
    if (car[i].second >= w) ans = min(ans, car[i].first);
  if (ans == 1e9 + 1)
    cout << -1 << endl;
  else
    cout << ans << endl;
  return 0;
}
