#include <bits/stdc++.h>
using namespace std;
int n, k, s, t, c[200001], v[200001], g[200001];
int cost(int dist, int x) {
  if (dist * 2 <= x)
    return dist;
  else if (dist > x)
    return t + 1;
  else
    return -x + dist + dist + dist;
}
bool can(int x) {
  long long sum = cost(g[1], x);
  for (int i = 2; i <= k; i++) sum += cost(g[i] - g[i - 1], x);
  sum += cost(s - g[k], x);
  return sum <= t;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d %d", &c[i], &v[i]);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  sort(g + 1, g + 1 + k);
  int s = 1, e = 1e9, ans = 1e9 + 1;
  while (s <= e) {
    int mid = (s + e) / 2;
    if (can(mid))
      ans = mid, e = mid - 1;
    else
      s = mid + 1;
  }
  int ret = 1e9 + 1;
  for (int i = 1; i <= n; i++)
    if (v[i] >= ans) ret = min(ret, c[i]);
  if (ret == 1e9 + 1) ret = -1;
  printf("%d", ret);
  return 0;
}
