#include <bits/stdc++.h>
using namespace std;
long long k, t;
bool can(long long h, long long arr[]) {
  long long dis = 0;
  long long pre = 0;
  long long pos = 0;
  long long ans = 0;
  for (int i = 0; i < k + 1; i++) {
    long long two = 0;
    long long ones = 0;
    dis = arr[i] - pre;
    pre = arr[i];
    if (dis > h) {
      return false;
    }
    if (dis * 2 > h) {
      two = (2 * dis) - h;
      ones = dis - two;
    } else {
      ones = dis;
    }
    ans += 2 * two + ones;
  }
  if (ans <= t) {
    return true;
  } else
    return false;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  long long n, s;
  cin >> n >> k >> s >> t;
  long long maxi = -1;
  long long mini = 2e9;
  vector<pair<long long, long long>> arr(n);
  for (int i = 0; i < n; i++) {
    cin >> arr[i].first;
    ;
    cin >> arr[i].second;
    maxi = max(maxi, arr[i].second);
    mini = min(mini, arr[i].second);
  }
  long long pos[k + 1];
  for (int i = 0; i < k; i++) {
    cin >> pos[i];
  }
  pos[k] = s;
  sort(pos, pos + k + 1);
  long long left = mini - 1;
  long long right = maxi + 1;
  long long mid;
  long long j = 7e10;
  if (t < s) {
    cout << -1 << endl;
    return 0;
  }
  while (right - left > 1) {
    mid = left + (right - left) / 2;
    if (can(mid, pos)) {
      right = mid;
      j = mid;
    } else {
      left = mid;
    }
  }
  long long answer = 7e10;
  for (int i = 0; i < n; i++) {
    if (arr[i].second >= j) {
      answer = min(arr[i].first, answer);
    }
  }
  if (answer == 7e10)
    cout << -1 << endl;
  else
    cout << answer << endl;
}
