#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<int> c(n);
  vector<int> v(n);
  for (int i = 0; i < n; i++) scanf("%d%d", &c[i], &v[i]);
  vector<int> g(k + 2);
  for (int i = 0; i < k; i++) scanf("%d", &g[i]);
  g[k] = 0;
  g[k + 1] = s;
  k += 2;
  sort(g.begin(), g.end());
  int q = 2e9;
  int start = 0;
  int end = 2e9;
  int mid = 2e9 / 2;
  for (int i = 0; i <= 32 && start < end; i++) {
    bool flag = true;
    int y = 0;
    for (int j = 1; j < k && flag; j++)
      if (g[j] - g[j - 1] > mid)
        flag = false;
      else
        y +=
            min(g[j] - g[j - 1], mid - g[j] + g[j - 1]) +
            2 * (g[j] - g[j - 1] - min(g[j] - g[j - 1], mid - g[j] + g[j - 1]));
    if (flag && y <= t) {
      end = mid;
      mid = (end + start) / 2;
      q = end;
    } else {
      start = mid;
      mid = (end + start) / 2;
    }
  }
  int min1 = 2e9 + 1;
  for (int i = 0; i < n; i++)
    if (v[i] >= q && c[i] < min1) min1 = c[i];
  if (min1 == 2e9 + 1)
    cout << "-1";
  else
    cout << min1;
  return 0;
}
