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;
long long n, k;
long long s, t;
long long c[1000000];
long long v[1000000];
long long pos[1000000];
long long len[1000000];
int can(long long v) {
  long long tm = 0;
  for (int i = 0; i <= k; i++) {
    if (v < len[i]) return 0;
    tm += 2 * len[i] - min(len[i], v - len[i]);
  }
  return tm <= t;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int i = 1; i <= k; i++) cin >> pos[i];
  sort(pos + 1, pos + 1 + k);
  for (int i = 1; i <= k; i++) len[i] = pos[i] - pos[i - 1];
  len[k + 1] = s - pos[k];
  k++;
  long long l = 0;
  long long r = 100000000000;
  long long m;
  if (!can(r)) {
    cout << -1 << endl;
    return 0;
  }
  while (r - l > 1) {
    m = (l + r) / 2;
    if (can(m))
      r = m;
    else
      l = m;
  }
  if (can(l))
    m = l;
  else
    m = r;
  long long ans = 1000000000000000000;
  for (int i = 0; i < n; i++) {
    if (v[i] >= m) ans = min(ans, c[i]);
  }
  if (ans < 1000000000000000000)
    cout << ans << endl;
  else
    cout << -1 << endl;
}
