#include <bits/stdc++.h>
using namespace std;
int c[200005], v[200005];
int n, k, s;
long long int t;
bool can(long long int m, vector<int> &dist) {
  int maxi = *max_element(dist.begin(), dist.end());
  if (maxi > m) return false;
  long long int time = 0;
  for (int i = 0; i < dist.size(); i++) {
    long long int d = dist[i];
    int l = 0, r = d, ans = -1;
    while (l <= r) {
      long long int x = l + (r - l) / 2;
      long long int y = d - x;
      if (2 * x + y <= m) {
        ans = x;
        l = x + 1;
      } else {
        r = x - 1;
      }
    }
    assert(ans >= 0);
    long long int x = ans, y = d - x;
    time += (x + 2 * y);
  }
  return (time <= t);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> c[i] >> v[i];
  }
  vector<int> sta(k);
  for (int i = 0; i < k; i++) cin >> sta[i];
  sort(sta.begin(), sta.end());
  vector<int> dist(k + 1);
  int past = 0;
  int pos = 0;
  for (int i = 0; i < k; i++) {
    int x = sta[i];
    dist[pos++] = x - past;
    past = x;
  }
  dist[pos] = s - past;
  long long int l = 1, r = 1e9;
  long long int mini = 1e9 + 5;
  while (l <= r) {
    long long int m = l + (r - l) / 2;
    if (can(m, dist)) {
      mini = m;
      r = m - 1;
    } else {
      l = m + 1;
    }
  }
  if (mini > 1e9) {
    cout << -1 << '\n';
    return 0;
  }
  int ans = 1e9 + 5;
  for (int i = 0; i < n; i++) {
    if (v[i] >= mini) {
      ans = min(ans, c[i]);
    }
  }
  if (ans > 1e9)
    cout << -1 << '\n';
  else
    cout << ans << '\n';
  return 0;
}
