#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
int n, k;
long long s, t;
long long c[MAXN], v[MAXN];
long long g[MAXN];
vector<long long> vs;
void init() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    scanf("%lld %lld", &c[i], &v[i]);
    vs.push_back(v[i]);
  }
  sort(vs.begin(), vs.end());
  vs.push_back(1e9 + 7);
  g[0] = 0;
  for (int i = 1; i <= k; i++) {
    scanf("%lld", &g[i]);
  }
  sort(g + 1, g + k + 1);
  g[k + 1] = s;
}
bool check(long long V) {
  long long sum = 0;
  for (int i = 0; i <= k; i++) {
    long long d = g[i + 1] - g[i];
    if (V < d) return 0;
    if (V > 2LL * d)
      sum += d;
    else
      sum += 3LL * d - V;
  }
  return sum <= t;
}
void solve() {
  int l = 0, r = n;
  while (l != r) {
    int mid = (l + r) >> 1;
    if (check(vs[mid]))
      r = mid;
    else
      l = mid + 1;
  }
  long long ans = 1e9 + 7;
  for (int i = 0; i < n; i++) {
    if (v[i] >= vs[r]) ans = min(ans, c[i]);
  }
  if (ans == 1e9 + 7 || r == n) {
    puts("-1");
    return;
  }
  cout << ans << '\n';
}
int main() {
  init();
  solve();
}
