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<pair<long long, long long>> car;
vector<int> kyori;
bool deter(long long a) {
  long long time = 0;
  for (int i = 0; i < k; ++i) {
    if (kyori[i] > a) return false;
    if (kyori[i] * 2 <= a) {
      time += kyori[i];
    } else {
      time += 2 * (kyori[i] * 2 - a) + (kyori[i] - (2 * kyori[i] - a));
    }
  }
  if (time <= t) return true;
  return false;
}
int main() {
  cin >> n >> k >> s >> t;
  for (long long i = 0; i < n; ++i) {
    long long a, b;
    cin >> a >> b;
    car.push_back(make_pair(a, b));
  }
  long long final_dist = 0;
  for (long long i = 0; i < k; ++i) {
    long long a;
    cin >> a;
    kyori.push_back(a);
    final_dist += a;
  }
  k++;
  kyori.push_back(s - final_dist);
  long long need_nenpi = 0;
  long long top = 1000000000000000000;
  long long bot = 0;
  while (top - bot > 1) {
    long long mid = (top + bot) / 2;
    if (deter(mid)) {
      top = mid;
    } else {
      bot = mid;
    }
  }
  if (deter(bot)) {
    need_nenpi = bot;
  } else {
    need_nenpi = top;
  }
  sort(car.begin(), car.end());
  for (int i = 0; i < car.size(); ++i) {
    if (need_nenpi <= car[i].second) {
      cout << car[i].first << endl;
      return 0;
    }
  }
  cout << "-1" << endl;
  return 0;
}
