#include <bits/stdc++.h>
using namespace std;
const int MAX = 200009;
int n, k;
long long s, t;
struct car {
  long long c, v;
  car() {}
  bool operator<(const car& o) const {
    if (v != o.v) return v < o.v;
    return c < o.c;
  }
} C[MAX];
long long g[MAX];
bool check(long long cap) {
  long long ti = 0;
  for (int i = 1; i < k; i++) {
    long long dist = g[i] - g[i - 1];
    if (dist > cap) return false;
    if (2 * dist <= cap) {
      ti += dist;
      continue;
    }
    ti += (cap - dist) + (dist - (cap - dist)) * 2LL;
  }
  return ti <= t;
}
long long Min[MAX];
int main() {
  ios::sync_with_stdio(false);
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    cin >> C[i].c >> C[i].v;
  }
  sort(C, C + n);
  reverse(C, C + n);
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[0] = 0;
  g[k + 1] = s;
  k += 2;
  sort(g, g + k);
  Min[0] = C[0].c;
  for (int i = 1; i < n; i++) Min[i] = min(Min[i - 1], C[i].c);
  int l = 0, r = n - 1, ans = -1;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (check(C[mid].v)) {
      ans = mid;
      l = mid + 1;
    } else {
      r = mid - 1;
    }
  }
  if (ans == -1)
    cout << -1 << endl;
  else
    cout << Min[ans] << endl;
  return 0;
}
