#include <bits/stdc++.h>
using namespace std;
pair<long long, long long> a[200 * 1000 + 7];
long long b[200 * 1000 + 7];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, k, s, T, t, i, j, L, M, R, ans = INT_MAX;
  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 + k + 1);
  b[k + 1] = s;
  L = 0;
  R = 1000 * 1000 * 1000;
  t = 0;
  for (i = 1; i <= k + 1; i++) {
    t +=
        2 * (b[i] - b[i - 1]) - min(R - (b[i] - b[i - 1]), b[i] - b[i - 1]) * 1;
  }
  if (t > T) {
    cout << -1;
    return 0;
  }
  while (R - L > 1) {
    M = (L + R) / 2;
    t = 0;
    for (i = 1; i <= k + 1; i++) {
      if (b[i] - b[i - 1] > M) {
        L = M;
        goto m1;
      }
      t += 2 * (b[i] - b[i - 1]) -
           min(M - (b[i] - b[i - 1]), b[i] - b[i - 1]) * 1;
    }
    if (t <= T)
      R = M;
    else
      L = M;
  m1:;
  }
  for (i = 1; i <= n; i++)
    if (a[i].second >= R && a[i].first < ans) ans = a[i].first;
  if (ans == INT_MAX)
    cout << -1;
  else
    cout << ans;
}
