#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
int n, k;
long long s, t, c[N], v[N], g[N], f[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> k >> s >> t;
  for (auto i = 1; i <= n; i++) cin >> c[i] >> v[i];
  for (auto i = 1; i <= k; i++) cin >> g[i];
  sort(g + 1, g + k + 1);
  g[++k] = s;
  for (auto i = 1; i <= n; i++) f[i] = v[i];
  sort(f + 1, f + n + 1);
  f[0] = unique(f + 1, f + n + 1) - f - 1;
  int l = 1, r = f[0], x = 0;
  while (l <= r) {
    int m = (l + r) >> 1, p = f[m], ok = 1;
    long long tm = 0ll;
    for (auto i = 1; i <= k; i++) {
      long long d = g[i] - g[i - 1];
      if (d > p) {
        ok = 0;
        break;
      }
      if (d * 2ll <= p)
        tm += 1ll * d;
      else
        tm += 3ll * d - p;
    }
    if (tm > 1ll * t) ok = 0;
    if (ok)
      x = m, r = m - 1;
    else
      l = m + 1;
  }
  if (x == 0) return puts("-1");
  long long ans = LONG_MAX;
  for (auto i = 1; i <= n; i++)
    if (v[i] >= f[x]) ans = min(ans, c[i]);
  cout << ans << endl;
  return 0;
}
