#include <bits/stdc++.h>
using namespace std;
const int64_t N = 1e6, M = 1e10;
int64_t c[N], v[N], g[N], d[N];
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int64_t n, k, s, t, h, l, m, r = M;
  cin >> n >> k >> s >> t;
  for (int64_t i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int64_t i = 1; i <= k; i++) cin >> g[i];
  g[k + 1] = s;
  sort(g, g + k + 2);
  for (int64_t i = 1; i < k + 2; i++) d[i] = g[i] - g[i - 1];
  sort(d + 1, d + k + 2);
  h = 2 * (l = d[k + 1]) + 1;
  while (l < h) {
    m = (l + h) / 2, s = 0;
    for (int64_t i = 1; i < k + 2; i++) s += 3 * d[i] - min(m, 2 * d[i]);
    if (s > t)
      l = m + 1;
    else
      h = m;
  }
  if (l == 2 * d[k + 1] + 1) return cout << -1, 0;
  for (int64_t i = 0; i < n; i++)
    if (v[i] >= l) r = min(r, c[i]);
  cout << (r == M ? -1 : r);
}
