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;
const int MN = 210000;
vector<pair<int, int> > a, b;
int n, k, s, t;
int posi[MN];
int ans = 2000000000 + 1;
int cost(int x) {
  int pre = 0;
  int ti = 0;
  for (int i = 0; i < k; i++) {
    int len = posi[i] - pre;
    if (len > b[x].second) return t + 1;
    int re = a[x].second - len;
    ti += max(len * 2 - re, len);
    pre = posi[i];
  }
  return ti;
}
void binary(int p, int q) {
  if (p >= q) return;
  int mid = (p + q) / 2;
  int temp = cost(mid);
  if (temp <= t) {
    ans = min(ans, b[mid].first);
    binary(p, mid);
  } else
    binary(mid + 1, q);
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    a.push_back(pair<int, int>(0, 0));
    scanf("%d%d", &a[i].first, &a[i].second);
  }
  for (int i = 0; i < k; i++) scanf("%d", &posi[i]);
  sort(a.begin(), a.end());
  sort(posi, posi + k);
  posi[k++] = s;
  int m = 0;
  int counter = 0;
  for (int i = 0; i < n; i++) {
    if (i < n && a[i].first == a[i + 1].first && a[i].second <= a[i + 1].second)
      continue;
    if (a[i].second > m) {
      m = a[i].second;
      b.push_back(a[i]);
    }
  }
  binary(0, n);
  if (ans == 2000000001)
    cout << -1 << endl;
  else
    cout << ans << endl;
  return 0;
}
