#include <bits/stdc++.h>
using namespace std;
int c[222222], v[222222], a[222222];
int main() {
  int n, k, s, t;
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    scanf("%d %d", c + i, v + i);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", a + i);
  }
  sort(a, a + k);
  a[k] = s;
  for (int i = k; i; i--) a[i] -= a[i - 1];
  int st = 0, ed = 0x7fffffff, mid;
  while (ed - st > 1) {
    mid = (st + ed) >> 1;
    long long T = 0;
    for (int i = 0; i <= k; i++) {
      if (a[i] > mid) {
        T = 0x7fffffff;
        break;
      } else if (mid < 2 * a[i]) {
        T += (3LL * a[i] - mid);
      } else
        T += a[i];
    }
    if (T <= t)
      ed = mid;
    else
      st = mid;
  }
  int ans = 0x7fffffff;
  for (int i = 0; i < n; i++) {
    if (v[i] >= ed) ans = min(ans, c[i]);
  }
  printf("%d\n", ans == 0x7fffffff ? -1 : ans);
  return 0;
}
