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;
using ll = long long;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ll n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<ll> c(n), v(n);
  for (ll i = 0; i < n; ++i) {
    cin >> c[i] >> v[i];
  }
  vector<ll> a(k);
  for (ll i = 0; i < k; ++i) {
    cin >> a[i];
  }
  a.push_back(0);
  a.push_back(s);
  sort(a.begin(), a.end());
  ll left = 0, right = (ll)1e9;
  while (left < right) {
    ll m = (left + right) / 2;
    ll tm = 0;
    for (ll i = 0; i < a.size() - 1; ++i) {
      ll len = a[i + 1] - a[i];
      if (len > m) {
        tm = t + 1;
        break;
      }
      if (m >= len * 2) {
        tm += len;
        continue;
      }
      tm += 3 * len - m;
    }
    if (tm <= t) {
      right = m;
    } else {
      left = m + 1;
    }
  }
  ll ans = (ll)2e9 + 7;
  for (ll i = 0; i < n; ++i) {
    if (v[i] >= left) {
      ans = min(ans, c[i]);
    }
  }
  if (ans > (ll)2e9) {
    cout << -1 << endl;
  } else {
    cout << ans << endl;
  }
}
