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 main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  int c[n], v[n], a[k + 3];
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int i = 0; i < k; i++) cin >> a[i];
  a[k] = 0;
  a[k + 1] = s;
  sort(a, a + k + 2);
  int l = 1, r = 1e9, m = (l + r) / 2, f;
  while (l < r) {
    f = 0;
    for (int i = 0; i < k + 1; i++) {
      if (m < (a[i + 1] - a[i])) {
        f = INT_MAX;
        break;
      }
      f += 2 * (a[i + 1] - a[i]) - min(a[i + 1] - a[i], m - (a[i + 1] - a[i]));
    }
    if (f <= t) {
      r = m;
      m = (l + r) / 2;
    } else {
      l = m + 1;
      m = (l + r) / 2;
    }
  }
  int res = INT_MAX;
  for (int i = 0; i < n; i++) {
    if (v[i] >= m) {
      res = min(res, c[i]);
    }
  }
  cout << (res == INT_MAX ? -1 : res);
  return 0;
}
