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 nax = 2e5 + 5;
int C[nax], V[nax], G[nax];
int n, k, s, t;
int slow;
bool valid(int cap) {
  int v = 0, loc = 0;
  for (int i = 0; i < k; i++) {
    int d = G[i] - loc;
    if (cap < d) return false;
    v += max(0, 4 * d - 2 * cap);
    loc = G[i];
  }
  int d = s - loc;
  if (cap < d) return false;
  v += max(0, 4 * d - 2 * cap);
  return v <= slow;
}
int main() {
  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);
  long long lo = 1, hi = 2 * s;
  if (t >= 2 * s)
    slow = t;
  else if (t < s)
    return printf("-1\n"), 0;
  else
    slow = 2 * t - 2 * s;
  while (lo < hi) {
    long long mid = (lo + hi) / 2;
    if (valid(mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  int ans = 2e9;
  for (int i = 0; i < n; i++)
    if (V[i] >= lo && C[i] < ans) ans = C[i];
  cout << ans << endl;
  return 0;
}
