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;
static const int INF = 0x3f3f3f3f;
static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
template <typename T, typename U>
static void amin(T &x, U y) {
  if (y < x) x = y;
}
template <typename T, typename U>
static void amax(T &x, U y) {
  if (x < y) x = y;
}
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<int> c(n), v(n);
  for (int(i) = 0; (i) < (int)(n); ++(i)) cin >> c[i] >> v[i];
  vector<int> zap(k + 2, 0);
  for (int(i) = 0; (i) < (int)(k); ++(i)) cin >> zap[i + 1];
  sort(zap.begin() + 1, zap.end() - 1);
  zap[k + 1] = s;
  for (int(i) = 0; (i) < (int)(k + 1); ++(i)) zap[i] = zap[i + 1] - zap[i];
  sort(zap.begin(), zap.end());
  vector<int> su_z(k + 1), suf_z(k + 1);
  su_z[0] = zap[0];
  for (int(i) = (int)(1); (i) < (int)(k + 1); ++(i))
    su_z[i] = su_z[i - 1] + zap[i];
  suf_z[k] = zap[k];
  for (int i = k - 1; i >= 0; i--) {
    suf_z[i] = suf_z[i + 1] + zap[i];
  }
  long long mi = INFL;
  int to;
  for (int(i) = 0; (i) < (int)(n); ++(i)) {
    to = 0;
    if (c[i] >= mi || zap[k] > v[i]) continue;
    int tt;
    if (zap[k] == v[i]) {
      tt = lower_bound(zap.begin(), zap.end(), v[i]) - zap.begin();
      to = 2 * suf_z[tt];
    } else
      tt = k + 1;
    for (int(j) = 0; (j) < (int)(tt); ++(j)) {
      to += 2 * zap[i] - min(v[i] - zap[i], zap[i]);
    }
    if (to > t)
      continue;
    else
      mi = c[i];
  }
  cout << (mi == INFL ? -1 : mi);
  return 0;
}
