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 <typename T>
T sqr(T x) {
  return x * x;
}
template <typename T>
T abs(T x) {
  return x > 0 ? x : -x;
}
const int maxn = 2e5 + 3;
int c[maxn], vv[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    cin >> c[i] >> vv[i];
  }
  vector<int> v;
  v.push_back(0);
  for (int i = 1; i <= k; i++) {
    int x;
    cin >> x;
    v.push_back(x);
  }
  v.push_back(s);
  sort(v.begin(), v.end());
  if (t < s) {
    cout << -1 << "\n";
    return 0;
  }
  if (t > 2 * s) {
    t = 2 * s;
  }
  vector<int> f;
  for (int i = 1; i < (int)v.size(); i++) {
    f.push_back(v[i] - v[i - 1]);
  }
  sort(f.begin(), f.end());
  vector<int> sum(f.size(), f[0]);
  for (int i = 1; i < (int)f.size(); i++) {
    sum[i] = sum[i - 1] + f[i];
  }
  int INF = 1e9 + 7;
  int ans = INF;
  for (int i = 1; i <= n; i++) {
    int value = vv[i];
    if (f.back() > value) {
      continue;
    }
    int pos = upper_bound(f.begin(), f.end(), value / 2) - f.begin();
    if (pos >= (int)f.size()) {
      ans = min(ans, c[i]);
      continue;
    }
    int cnt = (int)f.size() - pos;
    pos--;
    int delta =
        cnt * value - (sum[(int)f.size() - 1] - (pos >= 0 ? sum[pos] : 0));
    int quick = (pos >= 0 ? sum[pos] : 0) + delta;
    int cur = quick + (s - quick) * 2;
    if (cur <= t) {
      ans = min(c[i], ans);
    }
  }
  if (ans == INF) {
    ans = -1;
  }
  cout << ans << "\n";
  return 0;
}
