#include <bits/stdc++.h>
using namespace std;
bool Can(long long t, const vector<long long>& dists, long long cap) {
  if (cap < dists[dists.size() - 1]) {
    return false;
  }
  long long timetaken = 0;
  for (long long i = 0; i < dists.size(); ++i) {
    timetaken += max(dists[i], dists[i] * 3 - cap);
  }
  return timetaken <= t;
}
long long MinCap(long long t, const vector<long long>& dists) {
  long long LB = 0, UB = 1e9, result = LLONG_MAX;
  long long pos = (LB + UB) / 2;
  while (LB <= UB) {
    if (Can(t, dists, pos)) {
      result = pos;
      UB = pos - 1;
    } else {
      LB = pos + 1;
    }
    pos = (LB + UB) / 2;
  }
  return result;
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  long long c[n], v[n];
  for (long long i = 0; i < n; ++i) {
    cin >> c[i] >> v[i];
  }
  vector<long long> gas(k);
  for (long long i = 0; i < k; ++i) {
    cin >> gas[i];
  }
  sort(gas.begin(), gas.end());
  vector<long long> dists(k + 1);
  dists[0] = gas[0];
  for (long long i = 1; i < k; ++i) {
    dists[i] = gas[i] - gas[i - 1];
  }
  dists[k] = s - gas[k - 1];
  sort(dists.begin(), dists.end());
  long long mincap = MinCap(t, dists);
  long long ans = LLONG_MAX;
  for (long long i = 0; i < n; ++i) {
    if (v[i] >= mincap && c[i] < ans) {
      ans = c[i];
    }
  }
  if (ans == LLONG_MAX) ans = -1;
  cout << ans << endl;
}
