#include <bits/stdc++.h>
using namespace std;
long long n, len, tim, i, k, dis[200020];
pair<long long, long long> a[200020];
inline bool solve(long long cap) {
  long long i, ans = 0;
  for (i = 1; i <= k; i++) {
    long long dist = dis[i] - dis[i - 1];
    if (dist > cap) return false;
    long long slow = dist;
    long long fastt = min(slow, cap - slow);
    slow -= fastt;
    ans += (2 * slow) + fastt;
  }
  if (ans <= tim) return true;
  return false;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> k >> len >> tim;
  for (i = 1; i <= n; i++) {
    cin >> a[i].first;
    cin >> a[i].second;
  }
  for (i = 1; i <= k; i++) {
    cin >> dis[i];
  }
  sort(dis + 1, dis + k + 1);
  k++;
  dis[k] = len;
  long long low = 1, high = 9999999999;
  long long best_time = 99999999999;
  while (low <= high) {
    long long mid = (low + high) / 2;
    if (solve(mid)) {
      best_time = min(best_time, mid);
      high = mid - 1;
    } else
      low = mid + 1;
  }
  if (best_time == 99999999999) {
    cout << "-1";
    return 0;
  }
  long long ans = 99999999999;
  for (i = 1; i <= n; i++) {
    if (a[i].second >= best_time) {
      ans = min(ans, a[i].first);
    }
  }
  if (ans == 99999999999) {
    cout << -1;
    return 0;
  }
  cout << ans;
}
