#include <bits/stdc++.h>
using namespace std;
int n, nn, k, s, t, gas[200005];
pair<int, int> arr[200005];
vector<pair<int, int> > cars;
struct carsort {
  bool operator()(const pair<int, int> &a, const pair<int, int> &b) {
    if (a.first == b.first) {
      return a.second > b.second;
    } else
      return a.first < b.first;
  }
};
bool func(int car) {
  bool ret = true;
  int cap = cars[car].second;
  int tm = 0;
  int prev = 0;
  for (int i = 0; i < k; i++) {
    int dist = gas[i] - prev;
    if (dist > cap) {
      ret = false;
      break;
    } else {
      if (2 * dist <= cap) {
        tm += dist;
      } else {
        tm += (cap - dist) + (2 * dist - cap) * 2;
      }
    }
    prev = gas[i];
  }
  int dist = s - prev;
  if (dist > cap) {
    ret = false;
  } else {
    if (2 * dist <= cap) {
      tm += dist;
    } else {
      tm += (cap - dist) + (2 * dist - cap) * 2;
    }
  }
  if (tm > t) {
    ret = false;
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> arr[i].first >> arr[i].second;
  }
  for (int i = 0; i < k; i++) {
    cin >> gas[i];
  }
  sort(arr, arr + n, carsort());
  sort(gas, gas + k);
  int maxv = -1;
  for (int i = 0; i < n; i++) {
    if (arr[i].second > maxv) {
      cars.push_back(arr[i]);
      maxv = arr[i].second;
    }
  }
  nn = cars.size();
  int l = 0;
  int r = nn - 1;
  int ans = -1;
  while (l <= r) {
    int mid = (l + r) / 2;
    bool val = func(mid);
    if (val) {
      if (l == r) {
        ans = mid;
        l = mid + 1;
        break;
      }
      r = mid;
    } else {
      l = mid + 1;
    }
  }
  if (ans == -1)
    cout << ans;
  else
    cout << cars[ans].first;
}
