#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
long long n, k, s, t, c[N], v[N], x[N];
bool check(long long V) {
  int last = 0;
  long double T = 0;
  for (int i = 0; i < k; i++) {
    long double d = x[i] - last;
    if (V < d) return false;
    long double big = min(V - d, d);
    T += big;
    T += 2 * (d - big);
    last = x[i];
  }
  if (T <= t)
    return true;
  else
    return false;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int i = 0; i < k; i++) cin >> x[i];
  x[k++] = s;
  sort(x, x + k);
  int l = 0, r = 1e9 + 10;
  while (r - l > 1) {
    int mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  long long ans = 1e9 + 10;
  for (int i = 0; i < n; i++)
    if (v[i] >= r) ans = min(ans, c[i]);
  if (ans == 1e9 + 10)
    cout << "-1\n";
  else
    cout << ans << "\n";
  return 0;
}
