#include <bits/stdc++.h>
using namespace std;
struct node {
  int p, v;
} c[200005];
int a[200005];
int n, k, s, t;
int cmp(node x, node y) {
  if (x.v == y.v) return x.p < y.p;
  return x.v < y.v;
}
int make(int rode, int x) {
  if (rode > x) return 0;
  if (x >= rode * 2) return rode;
  int ans = x - rode;
  return ans + (rode - ans) * 2;
}
int vj(int mid) {
  int time = 0;
  int now = 0;
  for (int i = 0; i < k; i++) {
    int fl = make(a[i] - now, mid);
    now = a[i];
    if (fl)
      time += fl;
    else
      return 0;
  }
  if (time <= t) return 1;
  return 0;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) scanf("%d%d", &c[i].p, &c[i].v);
  for (int i = 0; i < k; i++) scanf("%d", a + i);
  a[k++] = s;
  sort(a, a + k);
  int r = 1000000000, l = 0;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (vj(mid)) {
      r = mid - 1;
    } else
      l = mid + 1;
  }
  r++;
  sort(c, c + n, cmp);
  int minn = 1000000009;
  for (int i = 0; i < n; i++) {
    if (c[i].v >= l) {
      if (c[i].p < minn) minn = c[i].p;
    }
  }
  if (minn == 1000000009)
    cout << -1 << endl;
  else
    cout << minn << endl;
  return 0;
}
