#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int n, k, s, t;
int cost[N];
int cap[N];
int g[N];
int f(int x) {
  int cur = 0;
  for (int i = 0; i <= k; i++) {
    int dist;
    if (i == 0)
      dist = g[i];
    else
      dist = g[i] - g[i - 1];
    if (dist > x) return 0;
    int two = min(dist, x - dist);
    int one = dist - two;
    cur += 2 * one + two;
  }
  return (cur <= t);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    cin >> cost[i] >> cap[i];
  }
  long long int lo = 1;
  long long int hi = INT_MAX;
  for (int i = 0; i < k; i++) {
    cin >> g[i];
  }
  g[k] = s;
  sort(g, g + k);
  int ans = INT_MAX;
  while (hi - lo > 2) {
    long long int mid = hi + lo;
    mid /= 2;
    if (!f(mid))
      lo = mid;
    else
      hi = mid;
  }
  while (!f(lo) and lo <= hi) lo++;
  for (int i = 1; i <= n; i++) {
    if (cap[i] >= lo) {
      ans = min(ans, cost[i]);
    }
  }
  if (ans == INT_MAX) ans = -1;
  cout << ans << endl;
}
