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 int MAXN = 5000001;
const long long int mod = 1000000007;
const long long int INF = INT_MAX;
inline long long int gcd(long long int a, long long int b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
inline long long int pow(long long int a, long long int n, long long int mod) {
  if (n == 0) return 1;
  long long int p = pow(a, n / 2, mod);
  p = (p % mod * p % mod) % mod;
  if (n % 2)
    return (p % mod * a % mod) % mod;
  else
    return p;
}
bool comp(pair<pair<long long int, long long int>, long long int> &a,
          pair<pair<long long int, long long int>, long long int> &b) {
  return a.first.second > b.first.second;
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int t = 1;
  long long int l = 1;
  while (t--) {
    long long int n, k, s, t;
    cin >> n >> k >> s >> t;
    vector<long long int> car;
    map<long long int, long long int> mp;
    for (long long int i = 0; i < n; i++) {
      long long int x, y;
      cin >> x >> y;
      if (mp.find(x) == mp.end()) {
        car.push_back(x);
        mp[x] = y;
      } else
        mp[x] = min(mp[x], y);
    }
    long long int n1 = car.size();
    vector<long long int> dis;
    dis.push_back(0);
    for (long long int i = 0; i < k; i++) {
      long long int x;
      cin >> x;
      dis.push_back(x);
    }
    dis.push_back(s);
    sort(dis.begin(), dis.end());
    sort(car.begin(), car.end());
    long long int low = 0;
    long long int high = n1 - 1;
    long long int ans = -1;
    while (low <= high) {
      long long int mid = (low + high) / 2;
      long long int p = mp[car[mid]];
      long long int curr_t = 0;
      long long int f = 0;
      for (long long int i = 1; i <= k + 1; i++) {
        long long int req = dis[i] - dis[i - 1];
        if (req > p) {
          f = 1;
          break;
        }
        long long int c1 = max((long long int)0, 2 * req - p);
        long long int c2 = req - c1;
        curr_t += (c1 * 2 + c2);
      }
      if (curr_t <= t && f == 0) {
        ans = car[mid];
        high = mid - 1;
      } else {
        low = mid + 1;
      }
    }
    if (ans == -1) {
      cout << -1;
      return 0;
    }
    cout << ans << "\n";
  }
}
