#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 200100;
const int inf = 2000000000;
pair<int, int> v[MAX_N];
int g[MAX_N];
int main() {
  ios::sync_with_stdio(false);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; ++i) {
    cin >> v[i].first >> v[i].second;
  }
  for (int i = 1; i <= k; ++i) {
    cin >> g[i];
  }
  g[0] = 0;
  g[k + 1] = s;
  sort(g, g + k + 2);
  vector<int> x;
  for (int i = 1; i <= k + 1; ++i) {
    int dx = g[i] - g[i - 1];
    x.push_back(dx);
  }
  sort(x.begin(), x.end());
  vector<int> sum(x.size());
  sum[0] = x[0];
  for (int i = 1; i < (int)x.size(); ++i) {
    sum[i] = sum[i - 1] + x[i];
  }
  int ans = inf;
  for (int i = 0; i < n; ++i) {
    if (x.back() > v[i].second) {
      continue;
    }
    long long res = 0;
    int pos1 = upper_bound(x.begin(), x.end(), v[i].second / 2) - x.begin() - 1;
    if (pos1 >= 0) {
      res += sum[pos1];
    }
    int pos2 = upper_bound(x.begin(), x.end(), v[i].second) - x.begin() - 1;
    if (pos2 >= 0 && x[pos2] > v[i].second / 2) {
      res += 3LL * (sum[pos2] - (pos1 >= 0 ? sum[pos1] : 0)) -
             (long long)v[i].second * (pos2 - pos1);
    }
    if (res <= t) {
      ans = min(ans, v[i].first);
    }
  }
  if (ans == inf) {
    cout << -1;
  } else {
    cout << ans;
  }
  return 0;
}
