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;
void die() {
  cout << -1 << endl;
  exit(0);
}
const int maxN = 100 * 1000 * 3 + 100;
pair<int, int> a[maxN];
int p[maxN];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  if (t < s) die();
  for (int i = 0; i < n; i++) cin >> a[i].second >> a[i].first;
  k++;
  for (int i = 1; i < k; i++) cin >> p[i];
  p[k++] = s;
  sort(p, p + k);
  sort(a, a + n);
  int st = -1, en = n;
  while (en - st > 1) {
    int m = (st + en) / 2;
    int cap = a[m].first;
    int speed = max(2 * s - t, 0);
    bool canDo = true;
    for (int i = 1; i < k; i++)
      if (p[i] - p[i - 1] > cap) {
        canDo = false;
        break;
      } else
        speed -= min(speed, min(p[i] - p[i - 1], cap - (p[i] - p[i - 1])));
    if (canDo && speed == 0)
      en = m;
    else
      st = m;
  }
  if (en == n) die();
  int mn = a[en].second;
  for (int i = en + 1; i < n; i++) mn = min(mn, a[i].second);
  cout << mn << endl;
}
