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 MAXN = 2 * 100000;
int c[MAXN + 1], v[MAXN + 1], n, k, s, t;
vector<int> res;
vector<pair<int, int> > gt;
bool check(int vol) {
  long long sum = 0;
  for (auto it : gt) {
    int dist = it.first;
    int l = 0, r = 1e9 + 1, mid;
    while (r > l + 1) {
      mid = (l + r) / 2;
      if (2 * mid + max(0, dist - mid) <= vol)
        l = mid;
      else
        r = mid;
    }
    sum += (long long)it.second * (min(l, dist) + (dist - min(l, dist)) * 2);
  }
  return sum <= t;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) scanf("%d%d", &c[i], &v[i]);
  res.push_back(0);
  res.push_back(s);
  for (int i = 0; i < k; i++) {
    int x;
    scanf("%d", &x);
    res.push_back(x);
  }
  sort(res.begin(), res.end());
  int mx = 0;
  map<int, int> calc;
  for (int i = 1; i < (int)res.size(); i++) {
    mx = max(mx, res[i] - res[i - 1]);
    calc[res[i] - res[i - 1]]++;
  }
  for (auto it : calc) gt.push_back({it.first, it.second});
  int l = mx - 1, r = 1e9 + 1, mid;
  while (r > l + 1) {
    mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid;
  }
  int ans = 1e9 + 1;
  for (int i = 0; i < n; i++)
    if (v[i] >= r) ans = min(ans, c[i]);
  if (ans == 1e9 + 1)
    cout << "-1\n";
  else
    cout << ans << "\n";
  return 0;
}
