#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 + k + 1);
  g[k + 1] = s;
  mg = 0;
  for (int i = k + 1; i; i--) mg = max(mg, g[i] -= g[i - 1]);
  int l = 0, r = 1e9, m;
  while (l <= r) {
    m = (l + r) / 2;
    if (ck(m)) {
      r = m - 1;
      mv = m;
    } else {
      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;
}
