#include <bits/stdc++.h>
using namespace std;
const int N = 1e6;
int n, k, s, t, pr[N + 2], cp[N + 2], gs[N + 2];
bool ok(int cc) {
  int tm = 0;
  for (int i = 1; i <= k; i++) {
    int ds = gs[i] - gs[i - 1];
    tm += ds * 2 - min(ds, cc - ds);
  }
  return tm <= t;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) cin >> pr[i] >> cp[i];
  for (int i = 1; i <= k; i++) cin >> gs[i];
  sort(gs + 1, gs + k + 1);
  int lo = 0, hi = 1e9, md;
  ++k;
  gs[k] = s;
  for (int i = 1; i <= k; i++) lo = max(lo, gs[i] - gs[i - 1]);
  while (hi - lo > 1) {
    md = (lo + hi) / 2;
    if (ok(md))
      hi = md;
    else
      lo = md;
  }
  for (md = lo; md <= hi; md++)
    if (ok(md)) break;
  int ans = 2e9;
  for (int i = 1; i <= n; i++) {
    if (cp[i] >= md) ans = min(ans, pr[i]);
  }
  if (ans > 1e9) ans = -1;
  cout << ans << endl;
  return 0;
}
