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 = 200010;
int c[maxn], v[maxn];
int g[maxn];
vector<int> dist;
long long pdist[maxn];
int main() {
  int n, k, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    scanf("%d%d", &c[i], &v[i]);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g, g + n);
  dist.push_back(g[0] - 0);
  for (int i = 1; i < n; i++) {
    dist.push_back(g[i] - g[i - 1]);
  }
  dist.push_back(s - g[n - 1]);
  sort(dist.begin(), dist.end());
  pdist[0] = dist[0];
  for (int i = 1; i < dist.size(); i++) pdist[i] = pdist[i - 1] + dist[i];
  long long ans = 1e15;
  for (int i = 0; i < n; i++) {
    int in = lower_bound(dist.begin(), dist.end(), v[i] / 2) - dist.begin();
    if (dist[(dist.size() - 1)] > v[i]) continue;
    long long time = pdist[in] + 3 * (s - pdist[in]) -
                     (long long)((int)dist.size() - in - 1) * v[i];
    if (time <= t) {
      if (c[i] < ans) ans = c[i];
    }
  }
  if (ans > (long long)(1e10)) {
    cout << -1;
    return 0;
  }
  cout << ans;
  return 0;
}
