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 MOD = 1000000007;
const int INF = 1000000001;
const long long LINF = 1000000000000000001LL;
int main() {
  ios_base::sync_with_stdio(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > car(n);
  for (int i = (0); i <= (n - 1); ++i) {
    cin >> car[i].first >> car[i].second;
  }
  vector<int> stat(k);
  for (int i = (0); i <= (k - 1); ++i) {
    cin >> stat[i];
  }
  sort(stat.begin(), stat.end());
  vector<int> dist(k + 1);
  for (int i = (0); i <= (k - 1); ++i) {
    dist[i] = stat[i] - (i ? stat[i - 1] : 0);
  }
  dist[k] = s - stat.back();
  sort(dist.begin(), dist.end());
  vector<int> distSum = dist;
  for (int i = (1); i <= (k); ++i) {
    distSum[i] += distSum[i - 1];
  }
  int minPrice = INF;
  for (auto &c : car) {
    int price = c.first, tank = c.second;
    if (tank < dist.back()) {
      continue;
    }
    int ind = upper_bound(dist.begin(), dist.end(), tank / 2) - dist.begin();
    int big = s - (ind ? distSum[ind - 1] : 0);
    int bigCnt = (int)(dist).size() - ind;
    long long timeTaken = s + (2 * big - (long long)tank * bigCnt);
    if (timeTaken <= t) {
      minPrice = min(minPrice, price);
    }
  }
  if (minPrice == INF) {
    cout << -1;
  } else {
    cout << minPrice;
  }
  return 0;
}
