#include <bits/stdc++.h>
using namespace std;
const int inf = (1 << 30) - 1;
const long long linf = (1ll << 62) - 1;
int main() {
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long>> cars(n);
  for (auto &i : cars) {
    scanf("%lld%lld", &i.first, &i.second);
  }
  vector<long long> g(k + 2);
  g[0] = 0;
  g[k + 1] = s;
  for (int i = 1; i <= k; i++) {
    scanf("%lld", &g[i]);
  }
  sort((g).begin(), (g).end());
  k += 2;
  long long l = 0, r = 1e10 + 100;
  while (r - l > 1) {
    long long m = (l + r) / 2;
    long long total_time = 0;
    for (int i = 0; i < k - 1; i++) {
      if (m < g[i + 1] - g[i]) {
        total_time = linf;
        break;
      }
      total_time += g[i + 1] - g[i];
      long long left = 2 * (g[i + 1] - g[i]) - m;
      total_time += max(0LL, left);
    }
    if (total_time > t) {
      l = m;
    } else {
      r = m;
    }
  }
  long long min_cost = linf;
  for (auto i : cars) {
    if (i.second >= r) {
      min_cost = min(min_cost, i.first);
    }
  }
  if (min_cost >= linf) {
    min_cost = -1;
  }
  cout << min_cost << endl;
  return 0;
}
