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() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  pair<int, int> a[n];
  for (int i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
  int g[k];
  for (int i = 0; i < k; i++) cin >> g[i];
  sort(g, g + k);
  int s1[k + 1];
  int c[k + 1];
  s1[0] = g[0];
  s1[k] = s - g[k - 1];
  for (int i = 1; i < k; i++) {
    s1[i] = g[k] - g[k - 1];
  }
  sort(s1, s1 + k + 1);
  for (int i = 0; i < k + 1; i++) c[i] = s1[i];
  int acc = 2 * s - t > 0 ? 2 * s - t : 0;
  int sm = -1;
  for (int i = 0; i < k; i++) {
    if (c[i] * 2 <= c[k]) {
      acc -= c[i];
      c[i] *= 2;
      sm = i;
    } else {
      acc -= c[k] - c[i];
      c[i] = c[k];
    }
  }
  if (acc > 0) {
    for (int i = sm + 1; i < k + 1; i++) {
      if (acc >= (2 * s1[i] - c[i]) * (k - sm)) {
        acc -= (2 * s1[i] - c[i]) * (k - sm);
        c[k] += (2 * s1[i] - c[i]);
        sm = i;
      } else {
        if (acc % (k - sm) == 0) {
          c[k] += acc / (k - sm);
          acc = 0;
        } else {
          c[k] += acc / (k - sm);
          acc = 0;
          c[k]++;
        }
      }
    }
  }
  int p = INT32_MAX;
  if (acc > 0) {
    cout << -1;
  } else {
    for (int i = 0; i < n; i++) {
      if (a[i].second >= c[k]) {
        p = min(p, a[i].first);
      }
    }
    if (p != INT32_MAX) {
      cout << p;
    } else {
      cout << -1;
    }
  }
}
