#include <bits/stdc++.h>
using namespace std;
using namespace std;
int main() {
  long long int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<long long int, long long int> > car(n);
  vector<long long int> zp(k);
  for (long long int i = 0; i < n; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    car[i].first = (long long int)(x);
    car[i].second = (long long int)(y);
  }
  long long int mlen = 0;
  for (long long int i = 0; i < k; i++) {
    int x;
    scanf("%d", &x);
    zp[i] = (x);
  }
  sort(zp.begin(), zp.end());
  for (long long int i = 0; i < k; i++) {
    if (i == 0)
      mlen = max(mlen, zp[i]);
    else
      mlen = max(mlen, zp[i] - zp[i - 1]);
  }
  mlen = max(mlen, s - zp[k - 1]);
  long long int l = 0, r = mlen * 2 + 1;
  while (r - l > 1) {
    long long int m = (l + r) / 2;
    int f = 1, time = 0;
    for (int i = 0; i < k; i++) {
      long long int x, y;
      if (i == 0) {
        x = min(zp[i], m - zp[i]);
        y = zp[i] - x;
      } else {
        x = min(zp[i] - zp[i - 1], m - (zp[i] - zp[i - 1]));
        y = zp[i] - zp[i - 1] - x;
      }
      if (x < 0 || y < 0) f = 0;
      time += y * 2 + x;
    }
    long long int x, y;
    x = min(s - zp[k - 1], m - s + zp[k - 1]);
    y = s - zp[k - 1] - x;
    if (x < 0 || y < 0) f = 0;
    time += y * 2 + x;
    if (time <= t && f == 1)
      r = m;
    else
      l = m;
  }
  if (r == mlen * 2 + 1) {
    cout << -1 << "\n";
    return 0;
  }
  long long int ans = 2000000001;
  for (int i = 0; i < n; i++) {
    if (car[i].second >= r) ans = min(ans, car[i].first);
  }
  if (ans == 2000000001)
    cout << -1;
  else
    cout << ans << "\n";
  return 0;
}
