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;
vector<pair<int, int>> m;
vector<int> z;
int T;
int n, k;
int bin1(int s, int v) {
  int l = 0;
  int r = s + 1;
  while (l + 1 < r) {
    int m = (l + r) / 2;
    if (m * 2 + (s - m) > v)
      r = m;
    else
      l = m;
  }
  if (l * 2 + (s - l) <= v) return (s - l) * 2 + l;
  return -1;
}
int ask(int v) {
  int t = 0;
  for (int i = z.size() - 1; i >= 0; --i) {
    int a = bin1(z[i], v);
    if (a == -1) return 0;
    t += a;
    if (t > T) return 0;
  }
  return 1;
}
int bin() {
  int l = -1;
  int r = n - 1;
  while (l + 1 < r) {
    int mi = (l + r) / 2;
    if (ask(m[mi].first))
      r = mi;
    else
      l = mi;
  }
  if (ask(m[r].first)) return r;
  return -1;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0), cout.tie(0);
  int s;
  cin >> n >> k >> s >> T;
  int c, v;
  for (int i = 0; i < n; ++i) {
    cin >> c >> v;
    m.push_back({v, c});
  }
  sort(m.begin(), m.end());
  int z1, z2;
  z1 = 0;
  vector<int> z3(k);
  for (int i = 0; i < k; ++i) {
    cin >> z3[i];
  }
  sort(z3.begin(), z3.end());
  for (int i = 0; i < k; ++i) {
    z.push_back(z3[i] - z1);
    z1 = z3[i];
  }
  z.push_back(s - z1);
  sort(z.begin(), z.end());
  int a = bin();
  if (a == -1)
    cout << -1;
  else {
    int minn = 1e9 + 8;
    for (int i = a; i < n; ++i) {
      minn = min(minn, m[i].second);
    }
    cout << minn << endl;
  }
  return 0;
}
