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 long long mod = 1000000007;
int n, k, s, t;
vector<pair<int, int> > c;
vector<int> v, g;
int gud(int x) {
  int pos = 0, vr = 0, slow, fast = 0;
  for (int i = (int)(0); i < (int)(k + 1); ++i) {
    if (x < g[i] - pos) return false;
    slow = g[i] - pos;
    if (x > slow) fast = min(x - slow, slow);
    slow -= fast;
    vr += fast + 2 * slow;
    if (vr > t) return false;
    pos = g[i];
  }
  if (vr > t) return false;
  return true;
}
int binarno() {
  int lo = 0, hi = s, mid;
  while (lo + 1 < hi) {
    mid = (lo + hi) / 2;
    if (gud(mid))
      hi = mid;
    else
      lo = mid;
  }
  return hi;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = (int)(0); i < (int)(n); ++i) {
    int a, b;
    scanf(" %d%d", &a, &b);
    c.push_back(make_pair(a, b));
  }
  for (int i = (int)(0); i < (int)(k); ++i) {
    int a;
    scanf(" %d", &a);
    g.push_back(a);
  }
  g.push_back(s);
  sort((g).begin(), (g).end());
  int bla = INT_MAX, car = binarno();
  for (int i = (int)(0); i < (int)(n); ++i) {
    if (c[i].second >= car) bla = min(bla, c[i].first);
  }
  if (bla == INT_MAX)
    cout << -1 << endl;
  else
    cout << bla << endl;
  return 0;
}
