#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long n, k, s, m;
  cin >> n >> k >> s >> m;
  vector<pair<long long, long long> > a(n);
  for (long long i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
  sort(a.begin(), a.end());
  for (long long i = 1; i < n; i++)
    a[i].second = max(a[i].second, a[i - 1].second);
  vector<long long> b(k);
  for (long long i = 0; i < k; i++) cin >> b[i];
  b.push_back(0);
  b.push_back(s);
  k += 2;
  sort(b.begin(), b.end());
  long long l = 0, r = n;
  while (l != r) {
    long long t = (l + r) / 2;
    long long v = a[t].second;
    long long q = 0;
    bool good = true;
    for (long long i = 0; i < k - 1; i++) {
      long long d = b[i + 1] - b[i];
      if (d > v) {
        good = false;
        break;
      }
      q += max(d, d * 2 - (v - d));
    }
    if (good && q <= m)
      r = t;
    else
      l = t + 1;
  }
  if (l == n)
    cout << -1;
  else
    cout << a[l].first;
  return 0;
}
