#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
int c[N], v[N];
int g[N];
int n, k, s, t;
bool check(int v) {
  long long cnt = 0;
  for (int i = 1; i <= k + 1; i++) {
    int len = g[i] - g[i - 1];
    if (len > v) return false;
    int tmp = v - len;
    if (tmp <= len)
      cnt += tmp + (len - tmp) * 2;
    else
      cnt += len;
  }
  if (cnt <= t)
    return true;
  else
    return false;
}
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 + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  int l = 0, r = 1e9;
  if (!check(r))
    puts("-1");
  else {
    while (l + 1 < r) {
      int mid = (l + r) >> 1;
      if (check(mid))
        r = mid;
      else
        l = mid;
    }
    int ans = 2e9;
    for (int i = 1; i <= n; i++)
      if (v[i] >= r) ans = min(ans, c[i]);
    if (ans == 2e9)
      puts("-1");
    else
      printf("%d\n", ans);
  }
  return 0;
}
