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(false);
  cin.tie(NULL);
  long long i, j, n, k, s, t, pre = 0;
  cin >> n >> k >> s >> t;
  long long c[n], v[n];
  vector<long long> vec;
  for (i = 0; i < n; i++) {
    cin >> c[i];
    cin >> v[i];
  }
  long long dv[k];
  for (i = 0; i < k; i++) cin >> dv[i];
  sort(dv, dv + k);
  for (i = 0; i < k; i++) {
    long long cur;
    cur = dv[i];
    vec.push_back(cur - pre);
    pre = cur;
  }
  vec.push_back(s - pre);
  long long str = 0, end = 1e11, ans = 1e10;
  for (i = 0; i < 200; i++) {
    long long mid = (str + end) / 2;
    long long t1 = 0, ok = 0;
    for (auto d : vec) {
      long long cc = mid;
      if (cc < d) {
        ok = -1;
        break;
      } else if (cc >= 2 * d) {
        t1 += d;
      } else {
        long long x1 = 2 * d - cc;
        t1 += d + x1;
      }
    }
    if (ok == -1 || t1 > t) {
      str = mid;
    } else {
      end = mid;
      ans = mid;
    }
  }
  long long res = 1e10, fc = -1;
  for (i = 0; i < n; i++) {
    if (v[i] >= ans && res >= c[i]) {
      res = c[i];
      fc = v[i];
    }
  }
  if (fc == -1) {
    cout << -1 << endl;
  } else {
    cout << res << endl;
  }
  return 0;
}
