#include <bits/stdc++.h>
using namespace std;
int c[200010], v[200010], gas[200010];
int n, k, s, t;
int judge(int x) {
  int timeUse = 0, len, fastS, slowS;
  for (int i = 1; i <= k + 1; i++) {
    len = gas[i] - gas[i - 1];
    if (x < len) return 0;
    fastS = x - len;
    slowS = 2 * len - x;
    if (slowS > 0)
      timeUse += (fastS + slowS * 2);
    else
      timeUse += len;
  }
  if (timeUse <= t)
    return 1;
  else
    return 0;
}
int main() {
  long long l, r, mid;
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) scanf("%d%d", &c[i], &v[i]);
  for (int i = 1; i <= k; i++) scanf("%d", &gas[i]);
  gas[k + 1] = s;
  sort(gas, gas + k + 2);
  l = 0;
  r = s * 2 + 1;
  while (l < r) {
    mid = (l + r) / 2;
    if (judge(mid))
      r = mid;
    else
      l = mid + 1;
  }
  int minPrice = INT_MAX;
  for (int i = 1; i <= n; i++)
    if (c[i] <= minPrice && v[i] >= l && r != s * 2 + 1) minPrice = c[i];
  if (minPrice == INT_MAX)
    cout << -1 << endl;
  else
    cout << minPrice << endl;
  return 0;
}
