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;
int c[200010], v[200010], k;
long long int g[200010];
long long int fun(long long int f) {
  long long int ret = 0, prev = 0, temp;
  for (int i = 0; i < k; i++) {
    if (f < g[i] - prev) return INT_MAX;
    temp = min(f - (g[i] - prev), (g[i] - prev));
    ret += 2 * ((g[i] - prev) - temp) + temp;
    prev = g[i];
  }
  return ret;
}
int main() {
  ios_base::sync_with_stdio(false);
  int n, ans = INT_MAX;
  long long int s, t, start, end, mid;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int i = 0; i < k; i++) cin >> g[i];
  sort(g, g + k);
  g[k++] = s;
  start = 1;
  end = 2 * s;
  while (start < end) {
    mid = start + (end - start) / 2;
    if (fun(mid) > t)
      start = mid + 1;
    else
      end = mid;
  }
  if (fun(start) > t)
    cout << "-1\n";
  else {
    for (int i = 0; i < n; i++)
      if (v[i] >= start) ans = min(ans, c[i]);
    if (ans == INT_MAX)
      cout << "-1\n";
    else
      cout << ans << "\n";
  }
  return 0;
}
