#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 10;
int main() {
  int n, k, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  vector<pair<int, int> > car(n + 2);
  car[0] = make_pair(0, 0);
  car[n + 1] = make_pair(INF, INF);
  for (int i = 1; i <= n; ++i) {
    scanf("%d%d", &car[i].second, &car[i].first);
  }
  sort(car.begin(), car.end());
  vector<int> oil(k + 2);
  oil[0] = 0;
  oil[k + 1] = s;
  for (int i = 1; i <= k; ++i) scanf("%d", &oil[i]);
  sort(oil.begin(), oil.end());
  vector<int> d(k + 1);
  for (int i = 0; i < k + 1; ++i) d[i] = oil[i + 1] - oil[i];
  int l = 0, r = n + 1;
  while (r - l > 1) {
    int m = (r + l) / 2;
    int b = car[m].first;
    long long cur = 0;
    bool f = true;
    for (int i = 0; i < k + 1; ++i) {
      if (d[i] > b)
        f = false;
      else {
        int d1 = b - d[i];
        if (d1 >= d[i])
          cur += d[i];
        else {
          int d2 = d[i] - d1;
          cur += d1 + 2 * d2;
        }
      }
    }
    if ((cur <= t) && (f)) {
      r = m;
      while (car[r - 1].first == car[r].first) r--;
    } else {
      l = m;
    }
  }
  int ans = car[r].second;
  for (int i = r; i <= n; ++i) ans = min(ans, car[i].second);
  if (ans == INF)
    cout << -1;
  else
    cout << ans;
  return 0;
}
