#include <bits/stdc++.h>
using namespace std;
int n, K, L, T, ans;
int car[200010][2], gas[200010];
bool check(int fuel) {
  int i, d, t = 0;
  for (i = 1; i <= K; i++) {
    d = gas[i] - gas[i - 1];
    if (d * 2 <= fuel)
      t += d;
    else if (d > fuel)
      return false;
    else
      t += (fuel - d) + 2 * (2 * d - fuel);
  }
  return t <= T;
}
int work() {
  int head = 1, tail = 1e9 + 7, mid;
  while (head < tail) {
    mid = (head + tail) >> 1;
    if (check(mid))
      tail = mid;
    else
      head = mid + 1;
  }
  return head;
}
int main() {
  int i, lim;
  scanf("%d%d%d%d", &n, &K, &L, &T);
  for (i = 1; i <= n; i++) scanf("%d%d", &car[i][0], &car[i][1]);
  for (i = 1; i <= K; i++) scanf("%d", &gas[i]);
  sort(gas + 1, gas + 1 + K);
  gas[++K] = L;
  lim = work();
  ans = 1e9 + 7;
  for (i = 1; i <= n; i++)
    if (car[i][1] >= lim) ans = min(ans, car[i][0]);
  printf("%d", ans < 1e9 + 7 ? ans : -1);
  return 0;
}
