#include <bits/stdc++.h>
using std::cin;
using std::cout;
using std::deque;
using std::endl;
using std::map;
using std::max;
using std::min;
using std::multiset;
using std::pair;
using std::queue;
using std::set;
using std::sort;
using std::stack;
using std::string;
using std::vector;
int n, k, s, t;
int c[200005] = {
    0,
};
int v[200005] = {
    0,
};
int g[200005] = {
    0,
};
bool isGood(int middle) {
  int time = 0;
  for (int i = 1; i <= k + 1; i++) {
    int len = g[i] - g[i - 1];
    if (len > middle) {
      return false;
    }
    if (middle >= len * 2) {
      time += len;
    } else {
      time += (len * 2 - middle) * 2 + (middle - len);
    }
  }
  if (time <= t) return true;
  return false;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    scanf("%d%d", c + i, v + i);
  }
  g[0] = 0;
  g[k + 1] = s;
  for (int i = 1; i <= k; i++) {
    scanf("%d", g + i);
  }
  sort(g, g + k + 2);
  const int up = 2123456789;
  int badBak = 0;
  int goodBak = up;
  while (badBak + 1 != goodBak) {
    int middle = (int)((1LL * badBak + goodBak) / 2);
    if (isGood(middle)) {
      goodBak = middle;
    } else {
      badBak = middle;
    }
  }
  if (goodBak == up) {
    cout << -1;
    return 0;
  }
  int cheap = up;
  for (int i = 0; i < n; i++) {
    if (v[i] >= goodBak && c[i] < cheap) {
      cheap = c[i];
    }
  }
  if (cheap == up) {
    cout << -1;
    return 0;
  }
  cout << cheap;
  return 0;
}
