#include <bits/stdc++.h>
using namespace std;
int n, k, s, t, sol, i, crt, p;
int v[200003], c[200003], g[200003], sum[200003];
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (i = 1; i <= n; i++) scanf("%d %d", &c[i], &v[i]);
  for (i = 1; i <= k; i++) scanf("%d", &g[i]);
  sort(g + 1, g + k + 1);
  k++;
  g[k] = s;
  for (i = k; i >= 1; i--) g[i] -= g[i - 1];
  sort(g + 1, g + k + 1);
  for (i = 1; i <= k; i++) sum[i] = sum[i - 1] + g[i];
  sol = 2000000005;
  for (i = 1; i <= n; ++i) {
    if (v[i] < g[k]) continue;
    p = upper_bound(g + 1, g + k + 1, v[i] / 2) - g;
    int total = (k - p + 1) * v[i], acc = total - (sum[k] - sum[p - 1]);
    crt = sum[p - 1] + acc + 2 * (sum[k] - sum[p - 1] - acc);
    if (crt <= t)
      if (c[i] < sol) sol = c[i];
  }
  if (sol == 2000000005)
    printf("-1\n");
  else
    printf("%d\n", sol);
  return 0;
}
