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;
long long n, k, s, t, cost[200001], volume[200001];
const long long INF = 1000000001;
vector<int> dist;
bool can(long long mid) {
  long long vol = mid;
  long long time = 0;
  for (int i = 1; i <= k + 1; i++) {
    long long dis = dist[i] - dist[i - 1];
    if (dis > vol)
      return false;
    else {
      long long fast = min(dis, vol - dis);
      long long slow = dis - fast;
      time += slow * 2 + fast;
    }
  }
  if (time > t)
    return false;
  else
    return true;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> cost[i] >> volume[i];
  dist.push_back(0);
  dist.push_back(s);
  for (int i = 1; i <= k; i++) {
    long long a;
    cin >> a;
    dist.push_back(a);
  }
  sort(dist.begin(), dist.end());
  int left = 0, right = INF;
  long long ok = right;
  while (left < right) {
    long long mid = (left + right) / 2;
    if (can(mid) == true) {
      right = mid;
      ok = mid;
    } else {
      left = mid + 1;
    }
  }
  long long ans = 2 * INF;
  bool answ = false;
  for (int i = 0; i < n; i++) {
    if (volume[i] >= ok) {
      if (cost[i] < ans) {
        ans = cost[i];
        answ = true;
      }
    }
  }
  if (answ == false) {
    cout << -1 << endl;
  } else {
    cout << ans << endl;
  }
}
