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 long long oo = 0x3f3f3f3f3f3f3f3f;
long long check(long long tank, vector<long long> dist) {
  long long ans = 0, cur = 0;
  for (auto p : dist) {
    long long d = p - cur;
    cur = p;
    if (tank < d) return oo;
    ans += 2 * d - min(d, tank - d);
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long> > car(n), good;
  for (long long i = 0; i < n; ++i) {
    long long c, v;
    cin >> c >> v;
    car[i] = pair<long long, long long>(c, v);
  }
  sort(car.begin(), car.end());
  for (long long i = 0; i < n; ++i) {
    if (i == 0 || car[i].second > car[i - 1].second) good.push_back(car[i]);
  }
  vector<long long> dist(k + 1);
  for (long long i = 0; i < k; ++i) cin >> dist[i];
  dist[k] = s;
  sort(dist.begin(), dist.end());
  long long l = -1, h = n - 1;
  if (check(car[h].second, dist) > t)
    cout << -1 << '\n';
  else {
    while (l + 1 < h) {
      long long m = (l + h) >> 1;
      if (check(car[m].second, dist) <= t)
        h = m;
      else
        l = m;
    }
    cout << car[h].first << '\n';
  }
  return 0;
}
