#include <bits/stdc++.h>
using namespace std;
long long n, k, s, t;
long long c[200005], v[200005], g[200005];
long long res = -1;
bool check(long long val) {
  long long ans = 0;
  for (int i = 1; i <= k; i++) {
    long long d = g[i] - g[i - 1];
    if (val < d) return 0;
    if (val == d)
      ans += d * 2;
    else {
      if (val >= 2 * d)
        ans += d;
      else {
        long long x = val - d;
        long long y = d - x;
        ans += x + y * 2;
      }
    }
  }
  return ans <= t;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) cin >> c[i] >> v[i];
  for (int i = 1; i <= k; i++) cin >> g[i];
  g[0] = 0;
  sort(g + 1, g + k + 1);
  k++;
  g[k] = s;
  long long l, r;
  l = 0;
  r = 2 * s;
  while (l <= r) {
    long long mid = (l + r) / 2;
    if (check(mid)) {
      res = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  if (res == -1) {
    cout << -1;
    return 0;
  }
  long long ans = 1e18;
  for (int i = 1; i <= n; i++)
    if (v[i] >= res) ans = min(ans, c[i]);
  if (ans == 1e18) {
    cout << -1;
    return 0;
  }
  cout << ans;
}
