#include <bits/stdc++.h>
template <typename T>
bool _max(T& a, T b) {
  return (a < b) ? a = b, true : false;
}
template <typename T>
bool _min(T& a, T b) {
  return (b < a) ? a = b, true : false;
}
unsigned S[200005];
std::pair<unsigned, unsigned> P[200005];
int main() {
  unsigned n, k, s, l = 0, ans = -1;
  unsigned long long t, wil, lazy = 0;
  scanf("%u%u%u%llu", &n, &k, &s, &t), S[0] = 0, S[k + 1] = s;
  for (unsigned i = 0; i < n; i++) scanf("%u%u", &P[i].second, &P[i].first);
  std::sort(P, P + n);
  for (unsigned i = 1; i <= k; i++) scanf("%u", S + i);
  std::sort(S + 1, S + k + 1);
  for (unsigned i = 0; i <= k; i++) S[i] = S[i + 1] - S[i];
  std::sort(S, S + k + 1);
  for (unsigned i = 0; i < n; i++) {
    if (S[k] > P[i].first || P[i].second >= ans) continue;
    while (l <= k && P[i].first >= 2 * S[l]) lazy += S[l++];
    wil = lazy;
    for (unsigned j = l; j <= k; j++) wil += 3 * S[j] - P[i].first;
    if (wil <= t) _min(ans, P[i].second);
  }
  printf("%d\n", (~ans) ? (int)ans : -1);
  return 0;
}
