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() {
  unsigned long n, k, s, t, price = -1, i, j, time;
  int dist[10], car[20];
  cin >> n >> k >> s >> t;
  for (i = 0; i < n; i++) cin >> car[2 * i] >> car[2 * i + 1];
  dist[k] = s;
  for (i = 0; i < k; i++) {
    cin >> dist[i];
    dist[k] -= dist[i];
  }
  for (i = 0; i < n; i++) {
    time = 0;
    for (j = 0; j <= k; j++) {
      if (2 * dist[j] <= car[2 * i + 1])
        time += dist[j];
      else
        time += 3 * dist[j] - car[2 * i + 1];
    }
    if (time <= t)
      if (price == -1 || price > car[2 * i]) price = car[2 * i];
  }
  cout << price;
  return 0;
}
