#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 7;
int main() {
  ios_base::sync_with_stdio(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > data(n);
  for (int i = 0; i < n; i++) {
    cin >> data[i].first >> data[i].second;
  }
  sort(data.begin(), data.end());
  vector<int> d(k);
  for (int i = 0; i < k; i++) {
    cin >> d[i];
  }
  sort(d.begin(), d.end());
  d.push_back(s);
  k++;
  int l = 0, r = INF;
  while (r - l > 1) {
    int mid = (r + l) / 2;
    int left = 0;
    int time = 0;
    bool fl = 0;
    for (int i = 0; i < k; i++) {
      int rast = d[i] - left;
      int x = mid;
      left = d[i];
      if (x < rast) {
        fl = 1;
        break;
      }
      x -= rast;
      if (rast <= x) {
        time += rast;
      } else {
        time += x + (rast - x) * 2;
      }
    }
    if (!fl && time <= t) {
      r = mid;
    } else {
      l = mid;
    }
  }
  for (int i = 0; i < n; i++) {
    if (data[i].second >= r) {
      cout << data[i].first << endl;
      return 0;
    }
  }
  cout << -1;
}
