#include <bits/stdc++.h>
using namespace std;
long long n, k, s, t;
long long ans = 1e15 + 1;
vector<pair<long long, long long> > car;
long long g[200010];
bool check(long long f) {
  long long T = 0;
  for (int i = 1; i <= k; i++) {
    long long delta = g[i] - g[i - 1];
    long long a = max(0 * 1LL, 2 * delta - f);
    long long b = delta - a;
    if (b < 0) return false;
    T += 2 * a + b;
  }
  if (T <= t) return true;
  return false;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  if (t < s) {
    cout << -1;
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    long long c, v;
    cin >> c >> v;
    car.push_back(pair<long long, long long>(c, v));
  }
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[++k] = s;
  sort(g + 1, g + k + 1);
  int l = 0, r = s + 1, mid;
  while (r - l > 1) {
    mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  for (int i = 0; i < n; i++) {
    if (car[i].second >= r) {
      ans = min(ans, car[i].first);
    }
  }
  if (ans == 1e15 + 1)
    cout << -1;
  else
    cout << ans << "\n";
}
