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() {
  int n, k, s, t, ans = -1, r = 0, l = 0;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > car;
  for (int i = 0; i < n; i++) {
    int q, w;
    cin >> q >> w;
    car.push_back({w, q});
  }
  vector<int> z, dist;
  for (int i = 0; i < k; i++) {
    int q;
    cin >> q;
    z.push_back(q);
  }
  z.push_back(0);
  z.push_back(s);
  sort(z.begin(), z.end());
  for (int i = 1; i < z.size(); i++) {
    dist.push_back(z[i] - z[i - 1]);
    l += z[i] - z[i - 1];
  }
  sort(dist.begin(), dist.end());
  int L;
  L = dist[dist.size() - 1];
  for (int i = 0; i <= dist.size(); i++) {
    if (i != 0) {
      r += dist[i - 1];
      l -= dist[i - 1];
    }
    if (i == dist.size() || L < dist[i] * 2) {
      while (!(3 * l + r - L * i <= t) &&
             (i == dist.size() || L < dist[i] * 2)) {
        L++;
      }
      if (3 * l + r - L * i <= t) {
        ans = L;
        break;
      }
    }
  }
  if (ans == -1)
    cout << -1;
  else {
    int c = 1e10;
    for (int i = 0; i < car.size(); i++) {
      if (car[i].first >= L && (c > car[i].second || c == 1e10))
        c = car[i].second;
    }
    if (c == 1e10)
      cout << -1;
    else
      cout << c;
  }
  return 0;
}
