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<pair<long long int, long long int> > arr;
bool func(long long int v, long long int pos[], long long int k,
          long long int t) {
  long long int d, x, curr = 0;
  long long int time = 0;
  for (long long int i = 0; i < k; i++) {
    d = pos[i] - curr;
    curr = pos[i];
    if (d > v) return 0;
    x = min(d, v - d);
    time += x + 2 * (d - x);
    if (time > t) return 0;
  }
  return 1;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n, k, s, t;
  cin >> n >> k >> s >> t;
  long long int minN[n];
  long long int c, v;
  for (long long int i = 1; i <= n; i++) {
    cin >> c >> v;
    arr.push_back(make_pair(v, c));
  }
  long long int pos[k + 1];
  for (long long int i = 0; i < k; i++) cin >> pos[i];
  pos[k] = s;
  sort(pos, pos + k + 1);
  sort(arr.begin(), arr.end());
  minN[n - 1] = arr[n - 1].second;
  for (long long int i = n - 2; i >= 0; i--)
    minN[i] = min(arr[i].second, minN[i + 1]);
  long long int low = 0, high = arr[n - 1].first + 5, mid;
  while (low < high) {
    mid = low + (high - low) / 2;
    if (func(mid, pos, k + 1, t))
      high = mid;
    else
      low = mid + 1;
  }
  long long int ans = low;
  low = 0, high = arr.size() - 1;
  while (low < high) {
    mid = low + (high - low) / 2;
    if (arr[mid].first >= ans)
      high = mid;
    else
      low = mid + 1;
  }
  if (arr[low].first < ans)
    cout << "-1";
  else
    cout << arr[low].second;
}
