#include <bits/stdc++.h>
using namespace std;
long long n, k, s, t;
long long c[200005], v[200005], g[200005];
bool C(long long vol) {
  long long tt = 0;
  for (long long i = 1; i <= k + 1; i++) {
    if (vol < g[i] - g[i - 1])
      return false;
    else if (vol >= 2 * (g[i] - g[i - 1]))
      tt += g[i] - g[i - 1];
    else {
      long long dis = (g[i] - g[i - 1]) * 2 - vol;
      tt += g[i] - g[i - 1] + dis;
    }
  }
  return tt <= t;
}
int main() {
  scanf("%I64d%I64d%I64d%I64d", &n, &k, &s, &t);
  for (long long i = 1; i <= n; i++) scanf("%I64d%I64d", &c[i], &v[i]);
  for (long long i = 1; i <= k; i++) scanf("%I64d", &g[i]);
  sort(g + 1, g + 1 + k);
  g[0] = 0;
  g[k + 1] = s;
  long long l = 1, r = 2 * 1000000000 + 1;
  while (r - l > 1) {
    long long mid = (l + r) / 2;
    if (C(mid))
      r = mid;
    else
      l = mid;
  }
  long long ans = 2 * 1000000000 + 1;
  for (long long i = 1; i <= n; i++)
    if (v[i] >= r) ans = min(ans, c[i]);
  if (ans == 2 * 1000000000 + 1)
    puts("-1");
  else
    printf("%I64d\n", ans);
  return 0;
}
