#include <bits/stdc++.h>
using namespace std;
int n, k, s, t;
long long d[200010];
int v[200010], c[200010], b[200010], g[200010];
bool check(int x) {
  int i;
  long long tt = 0;
  for (i = 1; i <= k + 1; i++) {
    if (x < d[i]) return 0;
    if (x >= 2 * d[i])
      tt += d[i];
    else
      tt += 3 * d[i] - x;
  }
  if (tt <= t) return 1;
  return 0;
}
int main() {
  int i;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (i = 1; i <= n; i++) {
    scanf("%d%d", &c[i], &v[i]);
  }
  for (i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  for (i = 1; i <= k + 1; i++) {
    d[i] = g[i] - g[i - 1];
  }
  int l = 1, r = 1e9 + 1, mn = 1e9 + 1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (check(mid)) {
      mn = mid;
      r = mid - 1;
    } else
      l = mid + 1;
  }
  int ans = 1e9 + 1;
  for (i = 1; i <= n; i++) {
    if (v[i] >= mn && c[i] < ans) ans = c[i];
  }
  if (ans > 1e9) ans = -1;
  printf("%d\n", ans);
  return 0;
}
