#include <bits/stdc++.h>
using namespace std;
long long maxTime;
vector<pair<int, int> > prune(vector<pair<int, int> > cars) {
  sort(cars.begin(), cars.end());
  vector<pair<int, int> > ret;
  int befTank = -123;
  for (auto& it : cars) {
    if (it.second > befTank) {
      befTank = it.second;
      ret.push_back(it);
    }
  }
  return ret;
}
bool can(pair<int, int> c, const vector<int>& gases) {
  int now = 0;
  int tank = c.second;
  long long tm = 0;
  for (auto& it : gases) {
    if (it - now > tank) {
      return false;
    }
    int rem = tank - (it - now);
    tm += 2ll * (it - now);
    tm -= min(rem, it - now);
    now = it;
  }
  return tm <= maxTime;
}
int main() {
  ios::sync_with_stdio(false);
  int n, k, s;
  cin >> n >> k >> s >> maxTime;
  vector<pair<int, int> > cars;
  for (int i = 0; i < n; i++) {
    int price, tank;
    cin >> price >> tank;
    cars.push_back(make_pair(price, tank));
  }
  cars = prune(cars);
  vector<int> gases;
  for (int i = 0; i < k; i++) {
    int pos;
    cin >> pos;
    gases.push_back(pos);
  }
  gases.push_back(s);
  sort(gases.begin(), gases.end());
  int lo = 0, hi = cars.size() - 1;
  int ans = -1;
  while (lo <= hi) {
    int md = (lo + hi) / 2;
    if (can(cars[md], gases)) {
      hi = md - 1;
      ans = cars[md].first;
    } else {
      lo = md + 1;
    }
  }
  cout << ans << endl;
  return 0;
}
