#include <bits/stdc++.h>
using namespace std;
long long pwr(long long base, long long p, long long mod = (1000000007LL)) {
  long long ans = 1;
  while (p) {
    if (p & 1) ans = (ans * base) % mod;
    base = (base * base) % mod;
    p /= 2;
  }
  return ans;
}
int n, k, gas[200005];
long long s, t;
pair<long long, long long> cars[200005];
vector<long long> dist;
int main() {
  scanf("%d%d%lld%lld", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++)
    scanf("%lld%lld", &cars[i].second, &cars[i].first);
  sort(cars + 1, cars + n + 1);
  for (int i = 1; i <= k; i++) scanf("%d", &gas[i]);
  sort(gas + 1, gas + k + 1);
  dist.push_back(gas[1]);
  for (int i = 2; i <= k; i++) dist.push_back(gas[i] - gas[i - 1]);
  dist.push_back(s - gas[k]);
  sort(dist.begin(), dist.end(), greater<long long>());
  long long sum = accumulate(dist.begin(), dist.end(), 0);
  int start = -1;
  long long ans = (1000000007LL);
  long long curr_time = 0;
  for (int i = 1; i <= n; i++) {
    if (cars[i].first < dist[0]) continue;
    for (auto it : dist) curr_time += 2 * it;
    if (curr_time <= t) ans = min(ans, cars[i].second);
    start = i;
    break;
  }
  if (start == -1) {
    printf("-1\n");
    return 0;
  }
  for (int i = start; i <= n; i++) {
    long long cap = cars[i].first;
    while (!dist.empty() && cap >= dist.back() * 2) {
      curr_time -= dist.back();
      sum -= dist.back();
      dist.pop_back();
    }
    if (curr_time - ((int)dist.size() * cap - sum) <= t)
      ans = min(ans, cars[i].second);
  }
  if (ans == (1000000007LL)) ans = -1;
  printf("%lld", ans);
  return 0;
}
