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;
char _;
const int maxN = 200 * 1000 + 5;
const int mod = 1000 * 1000 * 1000 + 7;
const int maxL = 20;
pair<int, int> a[maxN];
int g[maxN];
long long cn[maxN];
long long cnt[maxN];
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> a[i].second >> a[i].first;
  sort(a, a + n);
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[k + 1] = s;
  k += 2;
  sort(g, g + k);
  for (int i = 1; i < k; i++) {
    int dis = g[i] - g[i - 1];
    int ps = lower_bound(a, a + n, make_pair(dis, -1)) - a;
    cn[0] += -mod;
    cn[ps] -= -mod;
    int ps1 = lower_bound(a, a + n, make_pair(dis * 2, -1)) - a;
    cn[ps1] += dis;
    cnt[ps]++;
    cnt[ps1]--;
    cn[ps] -= dis;
    cn[ps1] += dis;
  }
  long long sum = 0, ted = 0;
  int ans = mod;
  for (int i = 0; i < n; i++) {
    sum += cn[i];
    ted += cnt[i];
    long long res = ted * a[i].first + sum;
    if (2 * s - res <= t) ans = min(ans, a[i].second);
  }
  if (ans == mod)
    cout << -1 << endl;
  else
    cout << ans << endl;
  return 0;
}
