#include <bits/stdc++.h>
using namespace std;
const long long MXN = 2e5 + 10;
long long n, k, s, t, Time;
long long cnt[MXN];
vector<pair<long long, long long>> Car;
vector<long long> dis, gas;
long long cal(long long x) {
  long long sum = 0;
  for (int i = 0; i < dis.size(); i++) {
    if (dis[i] > x) return -1383;
    sum += min(x - dis[i], dis[i]);
  }
  return sum;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k >> s >> t;
  Time = s * 2;
  for (int i = 0; i < n; i++) {
    long long x, y;
    cin >> x >> y;
    Car.emplace_back(x, y);
  }
  sort(Car.begin(), Car.end());
  for (int i = 0; i < k; i++) {
    long long x;
    cin >> x;
    gas.push_back(x);
  }
  gas.push_back(0);
  gas.push_back(s);
  sort(gas.begin(), gas.end());
  for (int i = 0; i < gas.size() - 1; i++) {
    dis.push_back(gas[i + 1] - gas[i]);
  }
  sort(dis.begin(), dis.end());
  long long p = 0;
  Time -= t;
  while (Time > 0 && p < dis.size()) {
    if (Time >= dis[p]) {
      cnt[p] = dis[p];
      Time -= dis[p];
    } else {
      cnt[p] += Time;
      Time = 0;
    }
    p++;
  }
  if (Time > 0) return cout << -1, 0;
  long long l = 0, r = 1e9 + 7, maxi;
  while (r - l > 1) {
    long long mid = (l + r) / 2;
    if (cal(mid) >= s * 2 - t)
      r = mid;
    else
      l = mid;
  }
  if (r == 1e9 + 7) return cout << -1, 0;
  maxi = r;
  for (int i = 0; i < n; i++) {
    if (Car[i].second >= maxi) {
      cout << Car[i].first;
      return 0;
    }
  }
  cout << -1;
  return 0;
}
