#include <bits/stdc++.h>
using namespace std;
const long long INF = 2e9 + 10;
const int N = 1e6;
long long n, k, s, t, b[N];
pair<long long, long long> car[N];
vector<pair<long long, long long> > vec;
long long road[N];
bool check(long long x) {
  long long sum = 0;
  for (int i = 1; i <= k; i++) {
    if (x < road[i]) return 0;
    if (x >= 2 * road[i]) {
      sum += road[i];
    } else {
      sum += x - road[i] + 2 * (2 * road[i] - x);
    }
  }
  return sum <= t;
}
int main() {
  ios::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) cin >> car[i].second >> car[i].first;
  long long last = 0;
  for (int i = 1; i <= k; i++) {
    cin >> b[i];
  }
  sort(b + 1, b + k + 1);
  for (int i = 1; i <= k; i++) {
    long long tt = b[i];
    road[i] = tt - last;
    last = tt;
  }
  k++;
  road[k] = s - last;
  sort(car + 1, car + n + 1);
  long long now = INF;
  for (int i = n; i >= 1; i--) {
    if (car[i].second < now) {
      vec.push_back(car[i]);
      now = car[i].second;
    }
  }
  int l = 0, r = vec.size() - 1, ans = -1;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (check(vec[mid].first)) {
      ans = mid;
      l = mid + 1;
    } else
      r = mid - 1;
  }
  if (ans == -1)
    puts("-1");
  else
    cout << vec[ans].second << endl;
  return 0;
}
