#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 4;
const long long INF = 1e16;
int n, k;
long long s, t, g[N];
long long mint(long long first, long long dis) {
  if (dis > first) return INF;
  if (2 * dis <= first) return dis;
  int del = first - dis;
  return max(2 * dis - del, dis);
}
bool check(long long first) {
  long long tot = 0;
  for (int i = 1; i <= k + 1; i++) {
    long long curr = mint(first, g[i] - g[i - 1]);
    if (curr == INF) return false;
    tot += curr;
    if (tot > t) return false;
  }
  return tot <= t;
}
long long findmin() {
  long long lo = 0, hi = INF;
  while (lo < hi) {
    long long mid = (lo + hi) / 2;
    if (check(mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  return lo;
}
pair<long long, long long> cars[N];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> cars[i].second >> cars[i].first;
  }
  sort(cars, cars + n);
  for (int i = 1; i <= k; i++) cin >> g[i];
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  long long mcap = findmin();
  long long ans = INF;
  for (int i = 0; i < n; i++) {
    if (cars[i].first >= mcap) {
      ans = min(ans, cars[i].second);
    }
  }
  if (ans == INF) ans = -1;
  cout << ans << '\n';
  return 0;
}
