#include <bits/stdc++.h>
using namespace std;
long long N, K, s, t, c[200010], v[200010], g[200010];
bool check(long long fuel) {
  int i;
  long long time = 0;
  for (i = 1; i <= K; i++) {
    long long d = g[i] - g[i - 1];
    long long b = fuel - d;
    if (b < 0) return 0;
    b = min(b, d);
    time += 2 * (d - b) + b;
  }
  return time <= t;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> N >> K >> s >> t;
  int i;
  for (i = 1; i <= N; i++) cin >> c[i] >> v[i];
  for (i = 1; i <= K; i++) cin >> g[i];
  g[++K] = s;
  sort(g + 1, g + K + 1);
  long long l = 1, r = (1LL << 34), mid;
  while (l < r) {
    mid = (l + r) / 2;
    if (check(mid))
      r = mid;
    else
      l = mid + 1;
  }
  int ind = -1;
  for (i = 1; i <= N; i++)
    if (v[i] >= r) {
      if (ind == -1 || c[ind] > c[i]) ind = i;
    }
  if (ind == -1)
    cout << -1 << "\n";
  else
    cout << c[ind] << "\n";
  return 0;
}
