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;
struct pi {
  int c, v;
} pp[200005];
int cmp(pi a, pi b) { return a.v < b.v; }
int g[200005];
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  int ans = 1000000001;
  for (int i = 1; i <= n; i++) {
    scanf("%d%d", &pp[i].c, &pp[i].v);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  g[k + 1] = s;
  sort(g + 1, g + 2 + k);
  for (int i = k + 1; i >= 1; i--) {
    g[i] = g[i] - g[i - 1];
  }
  sort(pp + 1, pp + 1 + n, cmp);
  sort(g + 1, g + 2 + k);
  long long sum = 0, sum1 = 0;
  int no = 1;
  for (int i = 1; i <= n; i++) {
    if (pp[i].v >= g[k + 1]) {
      long long ti;
      while (no <= k + 1 && pp[i].v >= 2 * g[no]) {
        sum += g[no];
        sum1 += 3 * g[no] - pp[i].v;
        no++;
      }
      ti = (long long)3 * s - (long long)pp[i].v * (k + 1);
      ti -= sum1;
      ti += sum;
      if (ti <= t) {
        ans = min(ans, pp[i].c);
      }
    }
  }
  if (ans > 1000000000) {
    printf("-1\n");
  } else
    cout << ans << endl;
}
