#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
static const int INF = 1000000010;
int main() {
  ios_base::sync_with_stdio(false);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pii> cars(n);
  for (int i = 0; i < n; ++i) {
    cin >> cars[i].second >> cars[i].first;
  }
  sort(cars.begin(), cars.end());
  vector<int> g(k);
  for (int i = 0; i < k; ++i) {
    cin >> g[i];
  }
  sort(g.begin(), g.end());
  g.push_back(s);
  ++k;
  vector<int> f(k);
  for (int i = 0, p = 0; i < k; ++i) {
    f[i] = g[i] - p;
    p = g[i];
  }
  sort(f.begin(), f.end());
  vector<int> integral(k + 1);
  for (int i = 0; i < k; ++i) {
    integral[i + 1] = integral[i] + f[i];
  }
  int answer = INF;
  for (const auto& car : cars) {
    const int c = car.second, v = car.first;
    if (f.back() > v) {
      continue;
    }
    int score = 0;
    const int p = upper_bound(f.begin(), f.end(), v / 2) - f.begin();
    const int q = integral[k] - integral[p];
    score += integral[p] - integral[0];
    score += 2 * q - ((v * (k - p)) - q);
    if (score <= t) {
      answer = min(answer, c);
    }
  }
  if (answer >= INF) {
    answer = -1;
  }
  cout << answer << endl;
  return 0;
}
