#include <bits/stdc++.h>
using namespace std;
int INF = 2e9 + 1, t, k;
int b[200020];
int cal(int dis, int cap) {
  if (dis > cap) return INF;
  if (dis == cap) return 2 * cap;
  if (dis * 2 <= cap) return dis;
  return dis * 2 - (cap - dis);
}
bool ch(int x) {
  long long int ans = 0;
  for (int i = 1; i < k; i++) {
    ans += cal(b[i + 1] - b[i], x);
  }
  if (ans <= t) return true;
  return false;
}
pair<int, int> a[200010];
int main() {
  int n, s, imin = INF;
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) {
    scanf("%d %d", &a[i].second, &a[i].first);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%d", &b[i]);
  }
  k += 2;
  b[k - 1] = 0;
  b[k] = s;
  sort(b + 1, b + 1 + k);
  int l = 1, r = 1e9 + 20;
  while (l < r) {
    int mid = (l + r) / 2;
    if (ch(mid))
      r = mid;
    else
      l = mid + 1;
  }
  for (int i = 1; i <= n; i++) {
    if (l <= a[i].first) imin = min(imin, a[i].second);
  }
  cout << (imin == INF ? -1 : imin);
}
