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;
long long n, k, s, t;
vector<long long> station;
bool can(long long gas) {
  long long time = 0;
  for (long long i = 1; i <= k + 1; i++) {
    long long dist = station[i] - station[i - 1];
    long long acc = min(gas - dist, dist);
    long long normal = dist - acc;
    if (acc < 0) return false;
    time += acc + 2 * normal;
  }
  return time <= t;
}
signed main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long>> car(n);
  for (long long i = 0; i < n; i++) cin >> car[i].first >> car[i].second;
  station = vector<long long>(k + 2);
  for (long long i = 1; i < k + 1; i++) {
    cin >> station[i];
  }
  station[k + 1] = s;
  sort(station.begin(), station.end());
  long long lo = 0, hi = 1e10, mid;
  long long mini = 1e11;
  while (lo <= hi) {
    mid = (lo + hi) / 2;
    if (can(mid)) {
      mini = mid;
      hi = mid - 1;
    } else {
      lo = mid + 1;
    }
  }
  long long ans = 1e10;
  sort(car.begin(), car.end());
  for (long long i = 0; i < n; i++) {
    if (car[i].second >= mini) {
      ans = car[i].first;
      break;
    }
  }
  if (ans != 1e10)
    cout << ans << '\n';
  else
    cout << -1 << '\n';
}
