#include <bits/stdc++.h>
using namespace std;
const int64_t inf = 2e12 + 42;
signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int64_t n, k, s, t;
  cin >> n >> k >> s >> t;
  int64_t c[n], v[n];
  for (int64_t i = 0; i < n; i++) cin >> c[i] >> v[i];
  int64_t g[k + 2];
  for (int64_t i = 1; i <= k; i++) cin >> g[i];
  g[0] = 0, g[k + 1] = s;
  sort(g, g + k + 2);
  int64_t p[n];
  iota(p, p + n, 0);
  sort(p, p + n, [&](int64_t a, int64_t b) { return v[a] < v[b]; });
  int64_t l = -1, r = n;
  while (r - l > 1) {
    int64_t m = (l + r) / 2;
    int64_t V = v[p[m]];
    int64_t T = 0;
    for (int64_t i = 1; i <= k + 1; i++) {
      int64_t dist = g[i] - g[i - 1];
      int64_t k2 = V - dist;
      int64_t k1 = dist - k2;
      if (k2 < 0) T = inf;
      if (k1 < 0) {
        k1 = 0, k2 = dist;
      }
      assert(T >= inf ||
             k1 + k2 == dist && 2 * k2 + k1 <= V && k1 >= 0 && k2 >= 0);
      T += 2 * k1 + k2;
    }
    if (T <= t)
      r = m;
    else
      l = m;
  }
  if (r == n) {
    cout << -1 << endl;
    return 0;
  }
  int64_t ans = inf;
  for (int64_t i = 0; i < n; i++)
    if (v[i] >= v[p[r]]) ans = min(ans, c[i]);
  if (ans == inf)
    cout << -1 << endl;
  else
    cout << ans << endl;
  return 0;
}
