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;
template <class T>
T &get(T &n) {
  cin >> n;
  return n;
}
const int hell = 1000000007;
const long long INF = (long long)hell * hell;
const int MAXN = 2e5 + 10;
bool predicate(int fuel, vector<int> &G, int T) {
  int K = G.size(), prev = 0, t = 0;
  for (int i = 0; i < K; ++i) {
    int distance = G[i] - prev;
    if (distance > fuel)
      return false;
    else {
      int extra = fuel - distance;
      t += distance * 2 - min(extra, distance);
    }
    prev = G[i];
  }
  return (t <= T);
}
int bin_search(int lo, int hi, vector<int> &G, int T) {
  while (hi - lo > 1) {
    int mid = lo + (hi - lo) / 2;
    if (predicate(mid, G, T))
      hi = mid;
    else
      lo = mid;
  }
  return hi;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int N, K, S, T;
  cin >> N >> K >> S >> T;
  vector<int> P(N), C(N), G(K);
  for (int i = 0; i < N; ++i) cin >> P[i] >> C[i];
  for (int i = 0; i < K; ++i) cin >> G[i];
  sort(G.begin(), G.end());
  G.push_back(S);
  int min_fuel = bin_search(0, S, G, T);
  int ans = hell;
  for (int i = 0; i < N; ++i) {
    if (C[i] >= min_fuel) {
      ans = min(ans, P[i]);
    }
  }
  if (ans == hell)
    cout << "-1";
  else
    cout << ans;
}
