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 calcTime(int vol, const vector<int>& deltas) {
  int ans = 0;
  for (int s : deltas) {
    if (s > vol) {
      return INT_MAX;
    }
    if (vol >= 2 * s) {
      ans += s;
    } else {
      int add = vol - s;
      ans += 2 * (s - add) + add;
    }
  }
  return ans;
}
int main() {
  cin.sync_with_stdio(0);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<pair<int, int> > cars(n);
  for (int i = 0; i < n; i++) {
    cin >> cars[i].second;
    cin >> cars[i].first;
  }
  sort(cars.begin(), cars.end());
  vector<pair<int, int> > cars2;
  for (int i = n - 1; i >= 0; i--) {
    if (i > 0 && cars[i - 1].first == cars[i].first) {
      continue;
    }
    if (cars2.size() > 0 && cars[i].second >= cars2.back().second) {
      continue;
    }
    cars2.push_back(cars[i]);
  }
  reverse(cars2.begin(), cars2.end());
  vector<int> fuel(k + 2);
  for (int i = 0; i < k; i++) {
    cin >> fuel[i];
  }
  fuel[k] = 0;
  fuel[k + 1] = s;
  sort(fuel.begin(), fuel.end());
  vector<int> deltas(k + 1);
  for (int i = 1; i < fuel.size(); i++) {
    deltas[i - 1] = (fuel[i] - fuel[i - 1]);
  }
  sort(deltas.begin(), deltas.end());
  n = cars2.size();
  int a = -1;
  int b = n - 1;
  while (a < b - 1) {
    int m = (a + b) / 2;
    int testT = calcTime(cars2[m].first, deltas);
    if (testT > t) {
      a = m;
    } else {
      b = m;
    }
  }
  if (b >= n || calcTime(cars2[b].first, deltas) > t) {
    cout << -2 << endl;
    return 0;
  }
  int bestV = cars2[b].first;
  int bestCost = cars2[b].second;
  for (int i = 0; i < n; i++) {
    if (cars2[i].first >= bestV && cars2[i].second <= bestCost) {
      bestCost = cars2[i].second;
    }
  }
  cout << bestCost << endl;
  return 0;
}
