#include <bits/stdc++.h>
using namespace std;
long long n, m, s, t;
long long ans1[200009], ans2[200009];
long long pos[200009];
bool check(long long mid) {
  long long cnt = 0;
  for (int i = 0; i < m + 1; i++) {
    long long k = pos[i + 1] - pos[i];
    if (k > mid)
      return false;
    else {
      long long cha = mid - k;
      if (mid - k > k)
        cnt += k;
      else
        cnt += cha + (k - cha) * 2;
    }
    if (cnt > t) return false;
  }
  return cnt <= t;
}
int main() {
  cin >> n >> m >> s >> t;
  for (long long i = 0; i < n; i++) {
    scanf("%lld%lld", &ans1[i], &ans2[i]);
  }
  for (long long i = 0; i < m; i++) {
    scanf("%lld", &pos[i]);
  }
  pos[m] = 0, pos[m + 1] = s;
  sort(pos, pos + m + 2);
  long long ks = 0, js = 2e9;
  while (ks < js) {
    long long mid = (ks + js) >> 1;
    if (check(mid))
      js = mid;
    else
      ks = mid + 1;
  }
  long long min_ = 2e9;
  for (long long i = 0; i < n; i++)
    if (ans2[i] >= ks)
      if (ans1[i] < min_) min_ = ans1[i];
  if (min_ == (long long)2e9) min_ = -1;
  cout << min_ << endl;
  return 0;
}
