1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cout.precision(9);
  cout << fixed;
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long> > cars(n);
  for (int i = 0; i < n; ++i) cin >> cars[i].first >> cars[i].second;
  vector<long long> fuels(k);
  for (int i = 0; i < k; ++i) {
    cin >> fuels[i];
  }
  sort(fuels.begin(), fuels.end());
  while (!fuels.empty() && fuels.back() >= s) {
    fuels.pop_back();
    --k;
  }
  fuels.push_back(s);
  ++k;
  vector<long long> f(k);
  f[0] = fuels[0];
  for (int i = 1; i < k; ++i) f[i] = fuels[i] - fuels[i - 1];
  sort(f.begin(), f.end());
  vector<long long> sums(k + 1);
  sums[0] = 0;
  for (int i = 1; i <= k; ++i) sums[i] = sums[i - 1] + f[i - 1];
  long long mx = f[k - 1];
  long long mnCost = 2000000000;
  for (int i = 0; i < n; ++i) {
    long long c = cars[i].first;
    long long v = cars[i].second;
    if (v < mx) continue;
    std::vector<long long>::iterator it =
        lower_bound(f.begin(), f.end(), v / 2 + (v & 1));
    long long time = 0;
    if (it == f.end()) {
      time = sums[k];
    } else {
      int num = it - f.begin();
      time = 3 * (sums[k] - sums[num]) - (k - num) * v + sums[num];
    }
    if (time > t) continue;
    mnCost = min(mnCost, c);
  }
  if (mnCost == 2000000000) mnCost = -1;
  cout << mnCost << "\n";
  return 0;
}
