#include <bits/stdc++.h>
using namespace std;
int n, m, s, t, c[200200], v[200200], g[200200];
bool ok(long long k) {
  long long rlt = 0;
  for (int i = 0; i <= m; i++) {
    long long dist = g[i + 1] - g[i];
    if (k < dist) return 0;
    long long y = min(dist, k - dist), x = dist - y;
    rlt += 2 * x + y;
  }
  return rlt <= t;
}
int main() {
  scanf("%d %d %d %d", &n, &m, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d %d", &c[i], &v[i]);
  for (int i = 1; i <= m; i++) scanf("%d", &g[i]);
  sort(g + 1, g + m + 1);
  g[0] = 0, g[m + 1] = s;
  long long st = -1, en = 1ll << 40;
  while (en - st > 1) {
    long long mid = st + en >> 1;
    if (ok(mid))
      en = mid;
    else
      st = mid;
  }
  int ans = 1e9 + 7;
  for (int i = 1; i <= n; i++)
    if (v[i] >= en) ans = min(ans, c[i]);
  if (ans == 1e9 + 7) ans = -1;
  printf("%d\n", ans);
  return 0;
}
