#include <bits/stdc++.h>
using namespace std;
const int INF = 1 << 30;
const int N = 2e5 + 10;
pair<int, int> a[N];
int g[N];
int n, m, s, t;
bool check(int cap) {
  long long sum = 0;
  for (int i = 1; i < m; ++i) {
    int dis = g[i] - g[i - 1];
    if (dis > cap) return false;
    if (dis * 2 <= cap) {
      sum += dis;
    } else {
      int x = cap - dis;
      int y = dis - x;
      sum += x + 2LL * y;
    }
  }
  return sum <= t;
}
int main() {
  scanf("%d%d%d%d", &n, &m, &s, &t);
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &a[i].first, &a[i].second);
  }
  sort(a, a + n);
  for (int i = 1; i < n; ++i) {
    a[i].second = max(a[i].second, a[i - 1].second);
  }
  g[0] = 0;
  for (int i = 1; i <= m; ++i) {
    scanf("%d", g + i);
  }
  sort(g + 1, g + m + 1);
  g[m + 1] = s;
  m += 2;
  int low = 0, high = n;
  while (low != high) {
    int mid = (low + high) / 2;
    if (check(a[mid].second)) {
      high = mid;
    } else {
      low = mid + 1;
    }
  }
  int ret = high == n ? -1 : a[high].first;
  printf("%d\n", ret);
  return 0;
}
