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;
const int maxn = 2e5 + 5;
int n, k;
long long s, t;
int g[maxn];
pair<int, int> a[maxn];
bool cmp(pair<int, int> a, pair<int, int> b) {
  if (a.first != b.first) return a.first < b.first;
  return a.second > b.second;
}
long long calc(long long v, long long d) {
  long long x = v - d;
  if (x < 0) return INT_MAX;
  if (x >= d) return d;
  return x + 2LL * (d - x);
}
long long check(long long v) {
  long long ans = 0;
  for (int i = 0; i <= k; i++) {
    long long tmp = calc(v, g[i + 1] - g[i]);
    if (tmp >= INT_MAX) return INT_MAX;
    ans += tmp;
  }
  return ans;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) scanf("%d%d", &a[i].first, &a[i].second);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  g[0] = 0;
  sort(g + 1, g + 1 + k);
  g[k + 1] = s;
  sort(a + 1, a + 1 + n, cmp);
  vector<pair<int, int> > vec;
  vec.push_back(a[1]);
  for (int i = 2; i <= n; i++) {
    if (a[i].first != a[i - 1].first) vec.push_back(a[i]);
  }
  for (int i = 1; i < vec.size(); i++)
    vec[i].second = max(vec[i - 1].second, vec[i].second);
  int l = 0, r = vec.size() - 1;
  while (l < r) {
    int mid = (l + r) >> 1;
    if (check(vec[mid].second) <= t)
      r = mid;
    else
      l = mid + 1;
  }
  if (check(vec[r].second) <= t)
    cout << vec[r].first << endl;
  else
    cout << -1 << endl;
  return 0;
}
