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 i, j, k, l, m, n, s, a[311111], b[322222], c[222222], d, e, t, nn, mm,
    x, ll;
string p, q, r, w, ww;
multiset<long long> ms;
pair<long long, long long> y[311111];
vector<long long> u[111], uu, o;
int main() {
  cin >> n >> k >> l >> t;
  for (i = 0; i < n; i++) {
    scanf("%I64d %I64d", &a[i], &b[i]);
  }
  c[0] = 0;
  for (i = 1; i <= k; i++) scanf("%I64d", &c[i]);
  c[k + 1] = l;
  k += 2;
  sort(c, c + k);
  for (i = 0; i < k - 1; i++) c[i] = c[i + 1] - c[i];
  k--;
  sort(c, c + k);
  d = c[k - 1];
  e = 111111111111111;
  while (e > d) {
    s = 0;
    m = (d + e) / 2;
    for (i = 0; i < k; i++) {
      if (m >= 2 * c[i])
        s += c[i];
      else {
        s += 3 * c[i] - m;
      }
    }
    if (s <= t)
      e = m;
    else
      d = m + 1;
  }
  m = d;
  s = 111111111111;
  d = 0;
  for (i = 0; i < n; i++) {
    if (b[i] >= m) {
      d = 1;
      s = min(s, a[i]);
    }
  }
  if (d == 0)
    cout << -1;
  else
    cout << s;
}
