#include <bits/stdc++.h>
using namespace std;
bool solve(int g[], int k, int c, int s, int t) {
  int cur = 0, tused = 0;
  for (int i = 0; i < k; i++) {
    if (g[i] > cur + c) return 0;
    tused += max(3 * (g[i] - cur) - c, g[i] - cur);
    cur = g[i];
  }
  if (s > cur + c) return 0;
  tused += max(3 * (s - cur) - c, s - cur);
  if (tused <= t) return 1;
  return 0;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, k, s, t, l = 0, r = 1e9 + 9, m, ans = -1;
  cin >> n >> k >> s >> t;
  pair<int, int> p[n];
  int g[k];
  for (int i = 0; i < n; i++) cin >> p[i].first >> p[i].second;
  for (int i = 0; i < k; i++) cin >> g[i];
  sort(g, g + k);
  sort(p, p + n);
  m = (l + r) / 2;
  while (l != r) {
    if (solve(g, k, m, s, t)) {
      r = m;
    } else {
      l = m + 1;
    }
    m = (l + r) / 2;
  }
  for (int i = 0; i < n; i++) {
    if (p[i].second >= m) {
      ans = p[i].first;
      break;
    }
  }
  cout << ans << endl;
}
