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;
vector<int> stations;
long long nb_stations, starting_time;
bool possible(long long capacity) {
  long long time = 0;
  for (int i = 0; i < nb_stations; ++i) {
    long long d = stations[i];
    if (capacity < d) return false;
    long long full_speed = min(capacity - d, d);
    if (full_speed < 0) return false;
    long long min_speed = d - full_speed;
    time += full_speed + 2 * min_speed;
    if (time > starting_time) return false;
  }
  return true;
}
int main(int argc, char *argv[]) {
  long long N, road_length;
  std::ios::sync_with_stdio(false);
  cin >> N >> nb_stations >> road_length >> starting_time;
  vector<pair<long long, long long>> cars(N);
  for (int i = 0; i < N; ++i) {
    cin >> cars[i].first >> cars[i].second;
  }
  ++nb_stations;
  stations.assign(nb_stations, 0);
  for (int i = 0; i < nb_stations - 1; ++i) {
    cin >> stations[i];
  }
  stations[nb_stations - 1] = road_length;
  sort(stations.begin(), stations.end());
  for (int i = nb_stations - 1; i > 0; --i) {
    stations[i] -= stations[i - 1];
  }
  long long lo = 0;
  long long hi = nb_stations + 1;
  while (lo < hi) {
    long long mid = lo + (hi - lo) / 2;
    if (possible(mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  long long price = 2e9;
  for (int i = 0; i < N; ++i) {
    if (cars[i].second >= lo) price = min(price, cars[i].first);
  }
  if (price == 2e9)
    cout << -1 << endl;
  else
    cout << price << endl;
  return 0;
}
