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;
using LL = long long;
using DD = long double;
using pii = pair<int, int>;
const LL INFLL = 0x7f7f7f7f7f7f7f7fLL;
const int INFint = 0x7f7f7f7f;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.precision(16);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pii> tank_cost(n);
  for (int i = 0; i < int(n); ++i)
    cin >> tank_cost[i].second >> tank_cost[i].first;
  vector<int> stations(k);
  for (int i = 0; i < int(k); ++i) cin >> stations[i];
  stations.push_back(0);
  stations.push_back(s);
  sort((stations).begin(), (stations).end());
  LL low = 1;
  LL high = LL(2e9);
  while (high - low >= 2) {
    LL mid = (low + high) / 2;
    bool fail = false;
    LL minutes = 0;
    for (int i = int(1); i < int((int((stations).size()))); ++i) {
      int span = stations[i] - stations[i - 1];
      if (span > int(mid)) {
        fail = true;
        break;
      }
      int extra_litres = int(mid) - span;
      int at_1min_per_km = min(extra_litres, span);
      minutes += at_1min_per_km + 2 * (span - at_1min_per_km);
    }
    if (minutes > t) fail = true;
    if (!fail)
      high = mid;
    else
      low = mid;
  }
  LL rr = INFLL;
  for (int i = 0; i < int((int((tank_cost).size()))); ++i) {
    if (tank_cost[i].first >= high) rr = min(rr, LL(tank_cost[i].second));
  }
  if (rr == INFLL)
    cout << "-1\n";
  else
    cout << rr << '\n';
  return 0;
}
