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;
const int MAXN = 2e5 + 123;
pair<int, int> car[MAXN];
int b[MAXN];
int d[MAXN];
int bs(int l, int r, int w, int k) {
  if (r - l == 1) return r;
  int mid = (r + l) / 2;
  int temp = 0;
  for (int i = 0; i < k; i++) {
    if (d[i] < mid) temp += min(d[i], mid - d[i]);
  }
  if (temp >= w) return bs(l, mid, w, k);
  return bs(mid, r, w, k);
}
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) {
    int c, v;
    cin >> c >> v;
    car[i].first = c;
    car[i].second = v;
  }
  for (int i = 0; i < k; i++) cin >> b[i];
  b[k++] = 0;
  b[k++] = s;
  sort(b, b + k);
  for (int i = 1; i < k; i++) {
    d[i - 1] = b[i] - b[i - 1];
  }
  k--;
  sort(d, d + k);
  if (s > t) {
    cout << -1;
    return 0;
  }
  int w2, maxv;
  if (2 * s < t) {
    w2 = 0;
    maxv = d[k - 1];
  } else {
    w2 = 2 * s - t;
    maxv = max(bs(0, d[k - 1] * 2, w2, k), d[k - 1]);
  }
  sort(car, car + n);
  for (int i = 0; i < n; i++) {
    if (car[i].second < maxv) continue;
    cout << car[i].first;
    return 0;
  }
  return 0;
}
