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;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(15);
  int C, G, L, T;
  cin >> C >> G >> L >> T;
  if (T < L) {
    cout << -1 << "\n";
    return 0;
  }
  vector<int> price(C), tank(C);
  for (int i = 0; i < C; i++) cin >> price[i] >> tank[i];
  vector<int> gas(G);
  for (int i = 0; i < G; i++) cin >> gas[i];
  sort((gas).begin(), (gas).end());
  gas.push_back(L);
  int lo = 1, hi = 2 * L;
  int res = hi;
  while (lo <= hi) {
    int mi = (lo + hi) / 2;
    bool ok = true;
    int time = 0;
    int loc = 0;
    for (int g : gas) {
      int dist = g - loc;
      if (dist > mi) {
        ok = false;
        break;
      } else {
        int spend = 2 * dist - min(dist, mi - dist);
        time += spend;
        loc = g;
      }
    }
    if (ok && time <= T) {
      res = mi;
      hi = mi - 1;
    } else
      lo = mi + 1;
  }
  int low = INT_MAX;
  for (int i = 0; i < C; i++) {
    if (tank[i] >= res) low = min(low, price[i]);
  }
  cout << low << endl;
  return 0;
}
