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(void) {
  ios::sync_with_stdio(false);
  long long n, k, s, t, i, j, temp, maxi = 0, mini = 99999999999999;
  bool key = false;
  map<long long, long long> cmap;
  map<long long, long long>::iterator it;
  cin >> n >> k >> s >> t;
  long long c[n], v[n], g[k + 2];
  g[0] = 0;
  g[k + 1] = s;
  for (i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (i = 1; i <= k; i++) cin >> g[i];
  sort(g, g + k + 2);
  for (i = 0; i <= k; i++) {
    temp = g[i + 1] - g[i];
    maxi = max(maxi, temp);
    cmap[temp]++;
  }
  if (s <= t) {
    long long first = maxi, last = maxi * 2, mid, sum;
    while (first <= last) {
      mid = (first + last) / 2;
      sum = 0;
      for (it = cmap.begin(); it != cmap.end(); it++) {
        temp = it->first * 2;
        temp = max(it->first, temp - (mid - it->first));
        sum = sum + temp * it->second;
      }
      if (sum == t)
        break;
      else if (sum > t)
        first = mid + 1;
      else if (sum < t)
        last = mid - 1;
    }
    while (mid < last && sum > t) {
      mid--;
      sum = 0;
      for (it = cmap.begin(); it != cmap.end(); it++) {
        temp = it->first * 2;
        temp = max(it->first, temp - (mid - it->first));
        sum = sum + temp * it->second;
      }
    }
    if (sum <= t) {
      mini = 99999999999999;
      for (i = 0; i < n; i++) {
        if (v[i] >= mid) {
          mini = min(mini, c[i]);
          key = true;
        }
      }
    }
  }
  if (key)
    cout << mini;
  else
    cout << "-1";
  return 0;
}
