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>
int const MAX = 1e5 + 5;
using namespace std;
vector<long long> dist;
bool check(long long m, long long time) {
  long long t = 0;
  for (long long i = 0; i < dist.size(); i++) {
    long long s = dist[i];
    long long fast = m - s;
    if (fast < 0) return false;
    if (fast > s) fast = s;
    t += 2 * s - fast;
  }
  if (t > time) return false;
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  long long ndist = t - s;
  long long fdist = 2 * s - t;
  if (ndist < 0) return cout << -1, 0;
  ;
  if (fdist < 0) fdist = 0;
  vector<pair<long long, long long> > v;
  long long g[k];
  long long x, y;
  for (long long i = 0; i < n; i++) {
    cin >> x >> y;
    v.push_back({x, y});
  }
  for (long long i = 0; i < k; i++) cin >> g[i];
  sort(g, g + k);
  dist.push_back(g[0]);
  for (long long i = 1; i < k; i++) dist.push_back(g[i] - g[i - 1]);
  dist.push_back(s - g[k - 1]);
  long long l = 0, r = 1e9;
  while (r - l > 1) {
    long long m = (r + l) >> 1;
    if (check(m, t))
      r = m;
    else
      l = m;
  }
  if (!check(l, t)) l++;
  long long ans = LLONG_MAX;
  for (long long i = 0; i < v.size(); i++)
    if (v[i].second >= l) ans = min(ans, v[i].first);
  if (ans == LLONG_MAX) return cout << -1, 0;
  ;
  return cout << ans, 0;
  ;
}
