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 N = 2e5 + 10;
int n, ng, s, t;
pair<int, int> c[N];
int d[N];
bool posi(int cap) {
  int tt = 0;
  for (int i = 0; i <= ng; i++) {
    if (d[i] > cap) return false;
    if (cap >= 2 * d[i]) {
      tt += d[i];
      if (tt > t) return false;
      continue;
    }
    tt += 3 * d[i] - cap;
    if (tt > t) return false;
  }
  return true;
}
int main() {
  ios::sync_with_stdio(false);
  cin >> n >> ng >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> c[i].second >> c[i].first;
  }
  for (int i = 0; i < ng; i++) {
    cin >> d[i];
  }
  sort(d, d + ng);
  int temp, ppos = 0;
  for (int i = 0; i < ng; i++) {
    temp = d[i];
    d[i] = d[i] - ppos;
    ppos = temp;
  }
  d[ng] = s - ppos;
  int h = 1e9 + 9;
  if (!posi(h)) {
    cout << -1;
    return 0;
  }
  int l = 0;
  int m = (l + h) / 2;
  while (h - l > 1) {
    if (posi(m)) {
      h = m;
      m = (l + h) / 2;
      continue;
    }
    l = m;
    m = (l + h) / 2;
  }
  int mini = 1e9 + 1;
  for (int i = 0; i < n; i++) {
    if (c[i].first >= h) {
      mini = min(mini, c[i].second);
    }
  }
  cout << (mini > 1e9 ? -1 : mini);
}
