#include <bits/stdc++.h>
using namespace std;
int n, k, s, t, c[200005], v[200005], g[200005], mg, ans = 1e9 + 1, mv;
bool ck(int v) {
  if (v < mg) return 0;
  int tol = 0;
  for (int i = 1; i <= k + 1; i++) {
    tol += max(g[i], 3 * g[i] - v);
    if (tol > t) return 0;
  }
  return 1;
}
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);
  g[k + 1] = s;
  for (int i = k + 1; i; i--) mg = max(mg, g[i] -= g[i - 1]);
  for (int l = 0, r = 1e9, m = l + r >> 1; l <= r;
       ck(m = l + r >> 1) ? r = m - 1, mv = m : l = m + 1)
    ;
  if (mv)
    for (int i = 1; i <= n; i++)
      if (v[i] >= mv) ans = min(ans, c[i]);
  if (ans > 1e9) ans = -1;
  printf("%d", ans);
  return 0;
}
