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 n, k, s, t;
int g[200001];
int sg[200001];
int c[200001];
int v[200001];
int st[200001];
const int INF = 1e9;
int main() {
  ;
  ;
  cin >> n >> k >> s >> t;
  for (int i = 0; i < n; i++) scanf("%d%d", c + i, v + i);
  for (int i = 1; i <= k; i++) {
    scanf("%d", g + i);
  }
  sort(g + 1, g + 1 + k);
  if (g[k] != s) {
    g[k + 1] = s;
    k++;
  }
  for (int i = 1; i <= k; i++) {
    int dist = g[i] - g[i - 1];
    for (int j = 0; j < n; j++) {
      if (st[i] > t) continue;
      int mxs = v[j] / 2;
      int x = max(0, v[j] - dist);
      int y = max(0, dist - x);
      if (dist > v[j])
        st[j] += INF;
      else {
        if (dist <= x)
          st[j] += dist;
        else
          st[j] += x + 2 * y;
      }
    }
  }
  int ret = INF;
  for (int i = 0; i < n; i++) {
    if (st[i] <= t) ret = min(ret, c[i]);
  }
  if (ret == INF)
    cout << -1 << endl;
  else
    cout << ret << endl;
}
