#include <bits/stdc++.h>
using namespace std;
using LL = long long;
constexpr int N = 1e5 + 5;
int n, g, L, t;
vector<pair<int, int>> cars;
vector<int> gas;
vector<int> distances;
bool possible(int v) {
  const int capacity = v;
  LL T = 0;
  for (auto D : distances) {
    if (D > capacity) return false;
    LL x = min(D, capacity - D);
    LL y = D - x;
    T += x + 2 * y;
    assert(x + y == D);
    assert(capacity >= 2 * x + y);
  }
  if (T > t) return false;
  return true;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n >> g >> L >> t;
  cars.resize(n);
  gas.resize(g);
  for (auto& p : cars) cin >> p.second >> p.first;
  for (auto& p : gas) cin >> p;
  gas.push_back(0);
  gas.push_back(L);
  g += 2;
  sort(begin(cars), end(cars));
  sort(begin(gas), end(gas));
  for (int i = 0; i + 1 < g; i++) {
    distances.push_back(gas[i + 1] - gas[i]);
  }
  int v = -1;
  int l = 1, r = 1e9;
  while (l <= r) {
    int m = (l + r) / 2;
    if (possible(m)) {
      v = m;
      r = m - 1;
    } else {
      l = m + 1;
    }
  }
  if (v == -1)
    cout << -1;
  else {
    int ans = 2e9 + 100;
    for (int i = 0; i < n; i++)
      if (cars[i].first >= v) ans = min(ans, cars[i].second);
    cout << (ans > 1e9 + 7 ? -1 : ans) << endl;
  }
}
