#include <bits/stdc++.h>
using namespace std;
pair<long long, long long> a[250001];
long long b[250001], n, i, k, s, t, l, r, mid, sum, big, nom, ans;
bool comp(pair<long long, long long> a, pair<long long, long long> b) {
  if (a.second < b.second) return 1;
  return 0;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; i++) cin >> a[i].first >> a[i].second;
  for (i = 1; i <= k; i++) cin >> b[i];
  sort(b + 1, b + 1 + k);
  for (i = 1; i <= k; i++) big = max(big, b[i] - b[i - 1]);
  big = max(big, s - b[k]);
  sort(a + 1, a + 1 + n, comp);
  l = 1;
  r = n;
  while (l <= r) {
    mid = (l + r) / 2;
    if (a[mid].second < big) {
      l = mid + 1;
      continue;
    }
    sum = 0;
    for (i = 1; i <= k; i++)
      sum += min(a[mid].second - (b[i] - b[i - 1]), b[i] - b[i - 1]);
    sum += min(a[mid].second - (s - b[k]), s - b[k]);
    sum = s * 2 - sum;
    if (sum <= t) {
      r = mid - 1;
      nom = mid;
    } else
      l = mid + 1;
  }
  if (nom == 0) {
    cout << "-1" << '\n';
    return 0;
  }
  ans = 9000000000000000000LL;
  for (i = nom; i <= n; i++) ans = min(ans, a[i].first);
  cout << ans << '\n';
  return 0;
}
