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::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long> > vec;
  for (int i = 0; i < n; i++) {
    long long a, b;
    cin >> a >> b;
    vec.push_back({a, b});
  }
  sort(vec.begin(), vec.end());
  long long dis[k + 2];
  dis[0] = 0;
  for (int i = 1; i <= k; i++) {
    cin >> dis[i];
  }
  dis[k + 1] = s;
  sort(dis, dis + k + 2);
  long long mx = 0;
  vector<long long> re;
  for (int i = 1; i < k + 2; i++) {
    mx = max(mx, dis[i] - dis[i - 1]);
    re.push_back(dis[i] - dis[i - 1]);
  }
  sort(re.begin(), re.end());
  if (t < s * 2) {
    long long num = (s * 2) - t;
    long long st = 0, en = 1e9, m, ans = -1;
    while (st <= en) {
      m = (st + en) / 2;
      long long v = 0;
      for (int i = 0; i < re.size(); i++) {
        long long f = (m - re[i]);
        if (f > re[i])
          v += (re[i]);
        else if (f >= 0)
          v += ((re[i] - f) * 2 + f);
        else
          v += (1e9);
      }
      if (v <= t) {
        ans = m;
        en = m - 1;
      } else
        st = m + 1;
    }
    mx = ans;
  }
  if (mx == -1) return cout << -1, 0;
  for (int i = 0; i < vec.size(); i++) {
    if (vec[i].second >= mx) return cout << vec[i].first, 0;
  }
  cout << -1;
  return 0;
}
