#include <bits/stdc++.h>
#pragma comment(linker, ”/ STACK : 38777216“
using namespace std;
const int N = 200005;
const int inf = 2 * 1000 * 1000 * 1000;
const int mod = 1000 * 1000 * 1000 + 7;
int n, k;
long long s, t;
pair<long long, long long> p[N];
long long g[N];
int main() {
  scanf("%d%d%lld%lld", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%lld%lld", &p[i].first, &p[i].second);
  sort(p + 1, p + n + 1);
  for (int i = 2; i <= n; i++) p[i].second = max(p[i].second, p[i - 1].second);
  for (int i = 1; i <= k; i++) scanf("%lld", &g[i]);
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  int ina = 1, inb = n;
  long long answ = -1;
  while (ina <= inb) {
    int mid = (ina + inb) / 2;
    long long T = 0;
    long long S = p[mid].second;
    bool flag = true;
    for (int i = 0; i <= k; i++) {
      long long d = g[i + 1] - g[i];
      if (d > S) {
        flag = false;
        break;
      }
      long long delta = S - d;
      delta = min(delta, d);
      T += delta + (d - delta) * (2ll);
    }
    if (T > t) flag = false;
    if (flag) {
      answ = p[mid].first;
      inb = mid - 1;
    } else
      ina = mid + 1;
  }
  cout << answ << endl;
  return 0;
}
