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>
#pragma comment(linker, "/STACK:167772160000")
using namespace std;
std::pair<int, int> cars[210000];
int places[210000];
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < (n); i++) cin >> cars[i].first >> cars[i].second;
  for (int i = 0; i < (k); i++) cin >> places[i];
  sort(places, places + k);
  places[k++] = s;
  for (int i = k - 1; i > 0; i--) places[i] -= places[i - 1];
  int low = 0;
  int high = 20;
  while (low < high) {
    int mid = (low + high) / 2;
    long long req = 0;
    for (int i = 0; i < (k); i++) {
      int x = places[i];
      if (x > mid) {
        req = 1E9;
        break;
      }
      if (mid >= 2 * x) {
        req += x;
      } else {
        req += x * 3 - mid;
      }
    }
    if (req > t)
      low = mid + 1;
    else
      high = mid;
  }
  long long best = 1E10;
  for (int i = 0; i < (n); i++) {
    if (cars[i].second >= low && cars[i].first < best) best = cars[i].first;
  }
  if (best > 1E9)
    cout << -1;
  else
    cout << best;
  return 0;
}
