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 N = 2e5 + 7;
const int INF = 1e9 + 7;
long long x[N];
long long sum[N];
long long c[N], v[N];
int main() {
  ios::sync_with_stdio(false);
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (int i = 0; i < k; i++) cin >> x[i];
  sort(x, x + k);
  x[k] = s;
  for (int i = k; i > 0; i--) x[i] -= x[i - 1];
  sort(x, x + k + 1);
  for (int i = 0; i <= k; i++) sum[i + 1] = sum[i] + x[i];
  long long ans = INF;
  for (int i = 0; i < n; i++) {
    if (x[k] > v[i]) continue;
    long long tm = 2 * s;
    long long pos = upper_bound(x, x + k + 1, v[i] / 2) - x;
    tm -= sum[pos];
    tm -= (k + 1 - pos) * v[i] - (sum[k + 1] - sum[pos]);
    if (tm <= t) ans = min(ans, c[i]);
  }
  if (ans == INF)
    cout << "-1\n";
  else
    cout << ans << "\n";
  return 0;
}
