#include <bits/stdc++.h>
using namespace std;
long long k;
long long c[200100];
long long b[200100];
long long aw[200100];
long long i, n, s, t, answer, d;
long long check(long long v, long long ti) {
  long long t, i, a, d;
  t = 0;
  for (i = 1; i <= k; i++) {
    d = aw[i] - aw[i - 1];
    if (d > v) {
      return 0;
    }
    if (d * 2 <= v) {
      t += d;
    } else {
      a = (2 * d) - v;
      t += (2 * a) + (d - a);
    }
    if (t > ti) return 0;
  }
  return 1;
}
int main() {
  ios_base::sync_with_stdio(false);
  ios_base::sync_with_stdio(false);
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin.tie(NULL);
  cout.tie(NULL);
  cout.tie(NULL);
  cout.tie(NULL);
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; i++) {
    cin >> c[i] >> b[i];
  }
  for (i = 1; i <= k; i++) {
    cin >> aw[i];
  }
  ios_base::sync_with_stdio(false);
  k++;
  aw[k] = s;
  sort(aw + 1, aw + 1 + k);
  long long l = 1;
  long long r = 3ll * s;
  while (l + 1 < r) {
    long long mid = (l + r) / 2;
    if (check(mid, t) == 0)
      l = mid;
    else
      r = mid;
  }
  d = -1;
  if (check(l, t) == 1)
    d = l;
  else if (check(r, t) == 1)
    d = r;
  if (d == -1)
    cout << "-1";
  else {
    answer = -1;
    for (i = 1; i <= n; i++) {
      if (b[i] >= d) {
        if ((answer == -1) || (answer > c[i])) answer = c[i];
      }
    }
    cout << answer;
  }
  return 0;
}
