#include <bits/stdc++.h>
using namespace std;
vector<int> g;
int n, k, s, t;
bool check(long long v) {
  int cur = 0;
  long long res = 0;
  for (auto go : g) {
    int dist = go - cur;
    int l = 0, r = dist + 1;
    while (l < r - 1) {
      long long m = (l + r) / 2;
      if (2 * m + (dist - m) <= v) {
        l = m;
      } else {
        r = m;
      }
    }
    if (2 * l + (dist - l) > v) {
      return 0;
    }
    res += l + 2 * (dist - l);
    cur = go;
  }
  return res <= t;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > cv;
  for (int i = 0; i < n; i++) {
    int c, v;
    cin >> c >> v;
    cv.push_back({c, v});
  }
  for (int i = 0; i < k; i++) {
    int x;
    cin >> x;
    g.push_back(x);
  }
  g.push_back(s);
  sort(g.begin(), g.end());
  long long l = -1, r = 2e9 + 7;
  while (l < r - 1) {
    long long m = (l + r) / 2;
    if (check(m)) {
      r = m;
    } else {
      l = m;
    }
  }
  int res = 2e9;
  for (int i = 0; i < n; i++) {
    if (cv[i].second >= r) {
      res = min(res, cv[i].first);
    }
  }
  cout << (res == 2e9 ? -1 : res) << '\n';
}
