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;
struct Car {
  long long cost, cap;
  bool operator<(const Car& rhs) const {
    return cap < rhs.cap || (cap == rhs.cap && cost > rhs.cost);
  }
};
const long long N = 1e6;
long long n, K, s, t;
long long gas[N];
bool check(long long cap) {
  long long spent = 0;
  for (long long i = 1; i < K; i++) {
    long long dist = gas[i] - gas[i - 1];
    if (dist > cap) return false;
    long long acc = min(cap - dist, dist);
    spent += acc + (dist - acc) * 2;
  }
  return spent <= t;
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> K >> s >> t;
  vector<Car> cars(n);
  for (long long i = 0; i < n; i++) {
    cin >> cars[i].cost >> cars[i].cap;
  }
  gas[0] = 0;
  for (long long i = 1; i <= K; i++) cin >> gas[i];
  K++;
  sort(gas, gas + K);
  gas[K++] = s;
  long long l = 0, r = 1e9 + 7;
  while (l < r) {
    long long mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid + 1;
  }
  if (l == 1e9 + 7)
    cout << -1 << endl;
  else {
    long long ans = 1e9 + 7;
    for (long long i = 0; i < n; i++)
      if (cars[i].cap >= l) ans = min(ans, cars[i].cost);
    if (ans == 1e9 + 7)
      cout << -1 << endl;
    else
      cout << ans << endl;
  }
}
