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;
ostream& operator<<(ostream& out, pair<int, int>& o) {
  out << "(" << o.first << ", " << o.second << ") ";
  return out;
}
template <class Int>
ostream& operator<<(ostream& out, vector<Int>& o) {
  for (auto it : o) out << it << " ";
  return out;
}
template <class Int>
istream& operator>>(istream& in, vector<Int>& i) {
  for (auto& it : i) in >> it;
  return in;
}
int test(vector<int>& g, long long c, long long t) {
  int cost = 0;
  for (int i = 1; i < g.size(); i++) {
    int diff = g[i] - g[i - 1];
    if (c < diff) return 0;
    if (c >= 2 * diff)
      cost += diff;
    else
      cost += 3 * diff - c;
  }
  return cost <= t;
}
int main() {
  cin.tie(0);
  cin.sync_with_stdio(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > v(n);
  for (auto& it : v) cin >> it.first >> it.second;
  sort(v.begin(), v.end());
  vector<pair<int, int> > tmp = v;
  v.clear();
  v.push_back(tmp[0]);
  for (int i = 0; i < tmp.size() - 1; i++) {
    if (v.back().first == tmp[i + 1].first && tmp[i + 1].second > tmp[i].second)
      v.back() = tmp[i + 1];
    if (v.back().first != tmp[i + 1].first && tmp[i + 1].second > tmp[i].second)
      v.push_back(tmp[i + 1]);
  }
  vector<int> g(k + 2);
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[0] = 0;
  g[k + 1] = s;
  sort(g.begin(), g.end());
  long long l = 0, r = v.size() - 1;
  if (!test(g, v[r].second, t)) {
    cout << -1 << endl;
    return 0;
  }
  while (l < r) {
    long long mid = (l + r) / 2;
    if (test(g, v[mid].second, t))
      r = mid;
    else
      l = mid + 1;
  }
  cout << v[l].first << endl;
}
