#include <bits/stdc++.h>
using namespace std;
struct car {
  int c, v;
};
bool operator<(car a, car b) { return a.v < b.v; }
int main() {
  ios::sync_with_stdio(false);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<car> arr(n);
  for (int i = 0; i < n; i++) cin >> arr[i].c >> arr[i].v;
  vector<int> g(k + 2);
  g[0] = 0;
  for (int i(1); i <= k; i++) cin >> g[i];
  k += 2;
  g[k - 1] = s;
  sort(arr.begin(), arr.end());
  sort(g.begin(), g.end());
  int l = -1, r = n;
  int cnt = 0;
  while (r - l > 1) {
    cnt++;
    int m = (r + l) / 2;
    int time = 0;
    for (int i(1); i < k; i++) {
      int d = g[i] - g[i - 1];
      int a = min(arr[m].v - d, d);
      int norm = d - a;
      if (arr[m].v < d) {
        time = 2000000007;
        break;
      }
      time += a + 2 * norm;
    }
    if (time > t)
      l = m;
    else
      r = m;
  }
  if (r == n)
    cout << -1 << endl;
  else {
    int ans = 1000000007;
    for (int i = r; i < n; ++i) ans = min(ans, arr[i].c);
    cout << ans << endl;
  }
  return 0;
}
