1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main() {
  ll n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int>> cars(n);
  vector<int> gas(k);
  for (auto& x : cars) {
    cin >> x.first >> x.second;
    x.second = -x.second;
  }
  sort(begin(cars), end(cars));
  int p0 = 0, p1 = 1;
  for (; p1 < cars.size(); ++p1) {
    if (cars[p0].first < cars[p1].first && cars[p0].second > cars[p1].second) {
      cars[++p0] = cars[p1];
    }
  }
  cars.erase(begin(cars) + p0 + 1, end(cars));
  for (auto& x : cars) x.second = -x.second;
  for (auto& x : gas) cin >> x;
  gas.push_back(s);
  gas.push_back(0);
  sort(begin(gas), end(gas));
  for (int i = 0; i <= n; ++i) {
    gas[i] = gas[i + 1] - gas[i];
  }
  gas.pop_back();
  const int max_dist = *max_element(begin(gas), end(gas));
  int first_car = 0;
  while (first_car < n && cars[first_car].second < max_dist) ++first_car;
  auto pred = [&](const pair<int, int>& p) {
    const ll cap = p.second;
    ll time = s;
    for (const auto dist : gas) {
      if (cap < 2 * dist) time += 2 * dist - cap;
      if (time > t) return true;
    }
    return time > t;
  };
  auto it = partition_point(begin(cars) + first_car, end(cars), pred);
  if (it == end(cars)) {
    cout << -1 << endl;
    return 0;
  }
  cout << it->first << endl;
  return 0;
}
