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 NMAX = 400000 + 5;
int n, k, s, t;
int g[NMAX];
vector<pair<int, int> > cars;
bool works(int cap) {
  long long int tmp = 0;
  for (int i = 2; i <= k; ++i) {
    long long int dst = g[i] - g[i - 1];
    if (cap < dst) return false;
    if (cap >= 2 * dst)
      tmp += dst;
    else
      tmp += (dst * 2LL - (cap - dst));
  }
  return tmp <= t;
}
int main() {
  ios_base ::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  cars.resize(n + 1);
  for (int i = 1; i <= n; ++i) cin >> cars[i].second >> cars[i].first;
  sort(cars.begin() + 1, cars.end());
  for (int i = 2; i <= k + 1; ++i) cin >> g[i];
  g[k + 2] = s;
  k += 2;
  sort(g + 1, g + k + 1);
  int st = 1;
  int dr = n;
  int ans = n + 1;
  int mid;
  while (st <= dr) {
    mid = (st + dr) >> 1;
    if (works(cars[mid].first)) {
      ans = mid;
      dr = mid - 1;
    } else
      st = mid + 1;
  }
  if (ans == n + 1) {
    cout << "-1\n";
    return 0;
  }
  int yay = cars[ans].second;
  for (int i = ans + 1; i <= n; ++i) yay = min(yay, cars[i].second);
  cout << yay << '\n';
  return 0;
}
