#include <bits/stdc++.h>
using namespace std;
int n, k, s, t;
int g[200005], c[200005], v[200005], l[200005];
int suml[200005];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    cin >> c[i] >> v[i];
  }
  for (int i = 1; i <= k; i++) {
    cin >> g[i];
  }
  k++;
  sort(g + 1, g + k);
  g[k] = s;
  for (int i = 1; i <= k; i++) {
    l[i] = g[i] - g[i - 1];
  }
  sort(l + 1, l + k + 1);
  for (int i = 1; i <= k; i++) {
    suml[i] = suml[i - 1] + l[i];
  }
  int mc = 1999999999;
  for (int i = 1; i <= n; i++) {
    int c = ::c[i];
    int v = ::v[i];
    if (v < l[k]) {
      continue;
    }
    int split = upper_bound(l + 1, l + k + 1, v / 2) - l;
    int t_fast = suml[split - 1];
    long long t_eco =
        3ll * (suml[k] - suml[split - 1]) - v * 1ll * (k - split + 1);
    if (t_fast + t_eco <= t) {
      mc = min(mc, c);
    }
  }
  if (mc == 1999999999) {
    mc = -1;
  }
  cout << mc;
}
