#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int n, k, t;
int a[200005];
long long trial(long long x) {
  long long ret = 0;
  for (int i = 0; i < k; i++) {
    if (a[i] > x) return 1e12;
    long long k = x - a[i];
    k = min(k, 1ll * a[i]);
    ret += 2 * a[i] - k;
  }
  return ret;
}
int main() {
  scanf("%d %d", &n, &k);
  scanf("%d %d", &a[k], &t);
  vector<pair<int, int> > v;
  for (int i = 0; i < n; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    v.push_back(pair<int, int>(a, b));
  }
  for (int i = 0; i < k; i++) scanf("%d", &a[i]);
  k++;
  sort(a, a + k);
  for (int i = k - 1; i; i--) a[i] -= a[i - 1];
  long long s = 0, e = 1e10;
  while (s != e) {
    long long m = (s + e) / 2;
    if (trial(m) <= t)
      e = m;
    else
      s = m + 1;
  }
  if (trial(s) > t) {
    puts("-1");
    return 0;
  }
  int ret = 2e9 + 22;
  for (auto &i : v) {
    if (i.second >= s) ret = min(ret, i.first);
  }
  if (ret > 2e9 + 2) {
    ret = -1;
  }
  cout << ret;
}
