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 time_estim(vector<int> &x, int t, int s, int cand) {
  int ans = 0;
  int cur = 0;
  int k = x.size();
  for (int i = 0; i <= k && x[i] <= s; i++) {
    int next;
    if (i == k) {
      next = s;
    } else {
      next = x[i];
    }
    int diff = next - cur;
    if (cand < diff) return -1;
    int fast = min(cand - diff, diff);
    int slow = diff - fast;
    int total_time = fast + slow * 2;
    ans += total_time;
    cur = next;
  }
  if (cur != s) {
    int diff = s - cur;
    if (cand < diff) return -1;
    int fast = min(cand - diff, diff);
    int slow = diff - fast;
    int total_time = fast + slow * 2;
    ans += total_time;
  }
  if (ans > t) {
    return -1;
  }
  return ans;
}
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > c(n);
  vector<int> x(k);
  int min_c = 1e9;
  int max_c = -1e9;
  for (int i = 0; i < n; i++) {
    cin >> c[i].first >> c[i].second;
    if (c[i].second > max_c) max_c = c[i].second;
    if (c[i].second < min_c) min_c = c[i].second;
  }
  for (int i = 0; i < k; i++) {
    cin >> x[i];
  }
  int l = min_c;
  int r = max_c;
  while (l < r) {
    int mid = (l + r) / 2;
    int ans = time_estim(x, t, s, mid);
    if (ans == -1) {
      l = mid + 1;
    }
    r = mid;
  }
  int min_p = 1e9;
  for (int i = 0; i < n; i++) {
    if (c[i].second >= l && c[i].first < min_p) {
      min_p = c[i].first;
    }
  }
  if (min_p == 1e9)
    cout << -1 << endl;
  else
    cout << min_p << endl;
  return 0;
}
