#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 6;
long long int n, k, s, t;
vector<pair<long long int, long long int> > v;
int g[N];
long long int get(long long int dist, long long int cap) {
  if (cap >= 2 * 1LL * dist) {
    return (dist);
  }
  long long int c_minus_d = cap - dist;
  if (c_minus_d < 0) return -1;
  long long int dist_by_normal = dist * 2 - cap;
  long long int dist_by_accel = dist - dist_by_normal;
  return (dist_by_normal * 1LL * 2 + dist_by_accel);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    int x, y;
    cin >> x >> y;
    v.push_back(make_pair(x, y));
  }
  for (int i = 1; i <= k; i++) {
    cin >> g[i];
  }
  g[0] = 0;
  g[k + 1] = s;
  sort(g, g + k + 2);
  long long int lo = 0;
  long long int hi = 1234567892345672822;
  long long int ans = 1234567892345678222;
  while (hi - lo > 2) {
    long long int mid = (lo + hi) / 2;
    long long int cur_time = 0;
    int fl = 0;
    for (int i = 1; i <= k + 1; i++) {
      long long int dist = g[i] - g[i - 1];
      long long int timeTaken = get(dist, mid);
      if (timeTaken >= 0) {
        cur_time += timeTaken;
      } else {
        fl = 1;
        break;
      }
    }
    if (fl or cur_time > t)
      lo = mid;
    else
      hi = mid;
  }
  while (lo <= hi) {
    long long int cur_time = 0;
    int fl = 0;
    for (int i = 1; i <= k + 1; i++) {
      long long int dist = g[i] - g[i - 1];
      long long int timeTaken = get(dist, lo);
      if (timeTaken >= 0) {
        cur_time += timeTaken;
      } else {
        fl = 1;
        break;
      }
    }
    if (fl or cur_time > t)
      lo++;
    else
      break;
  }
  int zz = v.size();
  for (int i = 0; i < zz; i++) {
    if (v[i].second >= lo) {
      ans = min(ans, v[i].first);
    }
  }
  if (ans >= 1234567892345678222) ans = -1;
  cout << ans;
}
