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;
template <class T, class L>
inline bool smax(T &x, L y) {
  return x < y ? (x = y, 1) : 0;
}
template <class T, class L>
inline bool smin(T &x, L y) {
  return y < x ? (x = y, 1) : 0;
}
const long long maxn = 2e5 + 17;
long long n, c[maxn], v[maxn], p[maxn], k, s, t;
long long tim(long long v) {
  long long o = 0, tot = 0;
  for (long long i = 0; i < k; o = p[i++]) {
    if (p[i] - o > v) return 2e9 + 1;
    if (2 * (p[i] - o) <= v)
      tot += p[i] - o;
    else
      tot += v % (p[i] - o) * 1 + ((p[i] - o) - v % (p[i] - o)) * 2;
  }
  return tot;
}
int32_t main() {
  ios::sync_with_stdio(0), cin.tie(0);
  cin >> n >> k >> s >> t;
  for (long long i = 0; i < n; i++) cin >> c[i] >> v[i];
  for (long long i = 0; i < k; i++) cin >> p[i];
  p[k++] = s;
  sort(p, p + k);
  long long lo = 1, hi = 1e9 + 1;
  while (hi - lo > 1) {
    long long mid = lo + hi >> 1;
    (tim(mid) <= t ? hi : lo) = mid;
  }
  long long ans = 2e9 + 1;
  for (long long i = 0; i < n; i++)
    if (v[i] >= hi) smin(ans, c[i]);
  cout << (ans == 2e9 ? -1 : ans) << '\n';
  return 0;
}
