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 g[200009], n, k, s, t;
long long ans = 1e10;
long long time(long long c) {
  long long sum = 0;
  for (int i = 1; i <= k + 1; i++) {
    long long d = g[i] - g[i - 1];
    if (c < d) return 0;
    long long d1 = min(c - d, d);
    long long d2 = d - d1;
    sum += d1 + 2 * d2;
  }
  return sum <= t;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  pair<int, int> arr[n + 9];
  g[0] = 0, g[k + 1] = s;
  for (int i = 0; i < n; i++) cin >> arr[i].first >> arr[i].second;
  for (int i = 1; i <= k; i++) cin >> g[i];
  sort(g, g + k + 2);
  long long low = 1, high = 1e10, m, cc;
  while (low <= high) {
    m = (low + high) / 2;
    if (time(m))
      high = m - 1, cc = m;
    else
      low = m + 1;
  }
  for (int i = 0; i < n; i++) {
    if (arr[i].second >= cc && arr[i].first < ans) ans = arr[i].first;
  }
  cout << (ans != 1e10 ? ans : -1);
  return 0;
}
