#include <bits/stdc++.h>
using namespace std;
int n, k;
long long s, t;
vector<pair<long long, long long>> a;
vector<long long> maxV;
vector<long long> g;
bool Check(const long long v) {
  long long ct = 0;
  long long pos = 0;
  for (int i = 0; i < (int)g.size(); ++i) {
    long long dist = g[i] - pos;
    if (dist > v) {
      return false;
    }
    long long v2 = (v - dist);
    v2 = min(v2, dist);
    long long v1 = dist - v2;
    ct += (v1 * 2 + v2);
    if (ct > t) {
      return false;
    }
    pos = g[i];
  }
  return true;
}
void Solve() {
  sort(g.begin(), g.end());
  g.push_back(s);
  sort(a.begin(), a.end());
  maxV.resize(n);
  maxV[0] = a[0].second;
  for (int i = 1; i < n; ++i) {
    maxV[i] = max(maxV[i - 1], a[i].second);
  }
  int bl = 0;
  int br = n - 1;
  int ba = -1;
  while (bl <= br) {
    int bm = (bl + br) >> 1;
    if (Check(maxV[bm])) {
      ba = bm;
      br = bm - 1;
    } else {
      bl = bm + 1;
    }
  }
  cout << (ba == -1 ? -1 : a[ba].first) << endl;
  exit(0);
}
bool Read() {
  if (!(cin >> n >> k >> s >> t)) {
    return false;
  }
  a.resize(n);
  for (int i = 0; i < n; ++i) {
    cin >> a[i].first >> a[i].second;
  }
  g.resize(k);
  for (int i = 0; i < k; ++i) {
    cin >> g[i];
  }
  return true;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  while (Read()) {
    Solve();
  }
  return 0;
}
