#include <bits/stdc++.h>
using namespace std;
long long t, n, m, u, v, q, r, ql, qr, k, l, s, w, z, x, y, d, p, c, b;
const int N = 2e5 + 500;
const int SN = 300;
const int NN = 1e4 + 4;
const long long mod = 10007;
const long long INF = 1LL << 52LL;
long long C[N], V[N], G[N];
vector<long long> S;
vector<long long> SS;
long long ss[N];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; ++i) cin >> C[i] >> V[i];
  for (int i = 0; i < k; ++i) {
    cin >> G[i];
  }
  sort(G, G + k);
  S.push_back(G[0]);
  S.push_back(s - G[k - 1]);
  long long fn = max(G[0], s - G[k - 1]);
  for (int i = 0; i < k - 1; ++i) {
    S.push_back(G[i + 1] - G[i]);
    fn = max(fn, G[i + 1] - G[i]);
  }
  sort(S.begin(), S.end());
  SS.resize(S.size());
  SS[0] = S[0];
  for (int i = 1; i < S.size(); ++i) SS[i] = SS[i - 1] + S[i];
  long long sol = INF;
  for (int i = 1; i <= n; ++i) {
    if (fn > V[i]) continue;
    long long sum = 2 * SS.back();
    int x = (upper_bound(S.begin(), S.end(), V[i] / 2) - S.begin() - 1);
    sum -= x >= 0 ? SS[x] : 0;
    sum -= (SS.size() - x - 1) * V[i] - (SS.back() - (x >= 0 ? SS[x] : 0));
    if (sum > t)
      continue;
    else
      sol = min(sol, C[i]);
  }
  if (sol == INF) sol = -1;
  cout << sol << '\n';
  return 0;
}
