#include <bits/stdc++.h>
using namespace std;
int n, k, s, t;
bool can(int c, vector<int> st) {
  long long ans = 0;
  for (int i = 1; i < (int)st.size(); i++) {
    int gap = st[i] - st[i - 1];
    if (gap > c) return false;
    if (c >= 2 * gap)
      ans += gap;
    else
      ans += 1LL * 3 * gap - c;
  }
  return ans <= t;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  vector<pair<int, int> > cars(n);
  for (int i = 0; i < n; i++) scanf("%d %d", &cars[i].second, &cars[i].first);
  vector<int> st(k + 2);
  int dist = 0;
  st[0] = 0;
  st[k + 1] = s;
  for (int i = 1; i <= k; i++) cin >> st[i];
  sort(st.begin(), st.end());
  sort(cars.begin(), cars.end());
  int low = 0, high = n;
  int ans = -1;
  while (high > low) {
    int mid = (high + low) / 2;
    if (can(cars[mid].first, st)) {
      ans = mid;
      high = mid;
    } else
      low = mid + 1;
  }
  if (ans == -1) {
    cout << -1;
    return 0;
  }
  int pr = 2000000000;
  for (int i = 0; i < n; i++)
    if (cars[i].first >= cars[ans].first) pr = min(pr, cars[i].second);
  printf("%d", pr);
  return 0;
}
