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;
long long n, k, s, t;
vector<long long> g;
bool check(long long x) {
  long long T = 0;
  for (long long i = 1; i <= k + 1; ++i) {
    long long d = g[i] - g[i - 1];
    if (d > x) {
      return false;
    }
    long long pt = 2 * d;
    pt -= min(x - d, d);
    T += pt;
  }
  return T <= t;
}
void solve() {
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long>> a(n);
  g.resize(k + 2);
  for (long long i = 0; i < n; ++i) {
    cin >> a[i].second >> a[i].first;
  }
  for (long long i = 0; i < k; ++i) {
    cin >> g[i];
  }
  g[k] = s;
  g[k + 1] = 0;
  sort(g.begin(), g.end());
  long long l = 0, r = 1e17;
  while (r - l > 1) {
    long long m = (r + l) / 2;
    if (check(m)) {
      r = m;
    } else {
      l = m;
    }
  }
  sort(a.begin(), a.end());
  for (long long i = 0; i < n; ++i) {
    if (a[i].first >= r) {
      cout << a[i].second;
      return;
    }
  }
  cout << -1;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
}
