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() {
  const int INF = 2e9;
  int n, k;
  long long s, t;
  cin >> n >> k >> s >> t;
  vector<long long> c(n), v(n);
  for (int i = 0; i < n; i++) cin >> c[i] >> v[i];
  vector<long long> g(k + 2), d(k + 1);
  for (int i = 0; i < k; i++) cin >> g[i];
  g[k] = 0;
  g[k + 1] = s;
  k += 1;
  sort(g.begin(), g.end());
  for (int i = 0; i < k; i++) d[i] = g[i + 1] - g[i];
  sort(d.begin(), d.end());
  vector<long long> pref(k);
  vector<long long> m(k);
  m[k - 1] = d[k - 1];
  for (int i = k - 2; i >= 0; i--) m[i] = max(m[i + 1], d[i]);
  for (int i = 0; i < k; i++) d[i] = d[i] * 2;
  pref[0] = d[0];
  for (int i = 1; i < k; i++) pref[i] = d[i] + pref[i - 1];
  int cost = INF;
  for (int i = 0; i < n; i++) {
    int pos = upper_bound(d.begin(), d.end(), v[i]) - d.begin();
    long long time = 0;
    long long left = pos > 0 ? pref[pos - 1] : 0;
    time += left / 2;
    long long right = (pref[k - 1] - left) / 2;
    long long oil = (k - pos) * v[i];
    long long x = oil - right;
    time += x + (right - x) * 2;
    if (c[i] < cost && time <= t && m[pos] <= v[i]) cost = c[i];
  }
  if (cost == INF)
    cout << "-1";
  else
    cout << cost;
}
