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 n, m, s, t;
vector<pair<int, int> > c;
vector<int> g;
vector<int> d;
const int inf = 1 << 30;
bool ok(int cap) {
  int time = 0;
  for (auto dis : d) {
    if (cap < dis) return false;
    if (cap >= 2 * dis)
      time += dis;
    else
      time += 3 * dis - cap;
  }
  return time <= t;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n >> m >> s >> t;
  c.resize(n);
  g.resize(m);
  for (auto& v : c) {
    cin >> v.second >> v.first;
  }
  for (auto& v : g) {
    cin >> v;
  }
  sort(c.begin(), c.end());
  g.push_back(0);
  g.push_back(s);
  sort(g.begin(), g.end());
  for (int i = 1; i < g.size(); i++) d.push_back(g[i] - g[i - 1]);
  int l = 0;
  int r = c.size() - 1;
  int piv = inf;
  int ans = inf;
  while (l <= r) {
    int mid = (l + r) >> 1;
    int cap = c[mid].first;
    if (ok(cap)) {
      piv = cap;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  for (int i = 0; i < c.size(); i++)
    if (c[i].first >= piv && ans > c[i].second) ans = c[i].second;
  if (ans == inf) ans = -1;
  cout << ans << endl;
}
