#include <bits/stdc++.h>
using namespace std;
const long long INF = (long long)1e18;
vector<long long> g;
long long go(long long x) {
  long long res = 0;
  for (int i = 1; i < g.size(); i++) {
    long long len = g[i] - g[i - 1];
    if (len > x) return INF;
    long long slow = max(0ll, 2 * len - x);
    res += len + slow;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(nullptr);
  long long n, s, t, k;
  cin >> n >> k >> s >> t;
  vector<long long> c(n);
  vector<long long> v(n);
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  g = {0, s};
  for (int i = 0; i < k; i++) {
    long long x;
    cin >> x;
    g.push_back(x);
  }
  long long lo = 0;
  long long hi = INF;
  sort(g.begin(), g.end());
  long long res = INF;
  while (hi - lo > 1) {
    long long mid = (lo + hi) / 2;
    if (go(mid) <= t)
      hi = mid;
    else
      lo = mid;
  }
  for (int i = 0; i < n; i++) {
    if (v[i] >= hi) res = min(res, c[i]);
  }
  if (res == INF) res = -1;
  cout << res << endl;
}
