#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int c[N], v[N], g[N], d[N];
int main() {
  int n, k, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  int l = 0, r = 0;
  for (int i = 0; i < n; i++) scanf("%d%d", &c[i], &v[i]), r = max(r, v[i]);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  g[0] = 0, g[++k] = s;
  sort(g, g + k + 1);
  for (int i = 0; i < k; i++) d[i] = g[i + 1] - g[i];
  while (l <= r) {
    int mid = l + r >> 1;
    int s = 0;
    for (int i = 0; i < k; i++) {
      if (mid >= d[i])
        s += max(3 * d[i] - mid, d[i]);
      else {
        s = t + 1;
        break;
      }
    }
    if (s <= t)
      r = mid - 1;
    else
      l = mid + 1;
  }
  int ans = -1;
  for (int i = 0; i < n; i++)
    if (v[i] >= r + 1 && (ans == -1 || c[i] < ans)) ans = c[i];
  printf("%d\n", ans);
  return 0;
}
