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 long long INF = 1e18 + 1;
long long c[200010], v[200010], g[200010], cum[200010];
vector<long long> d;
int main() {
  long long n, k, s, t, ans = 1000000007, val, x;
  scanf("%lld%lld%lld%lld", &n, &k, &s, &t);
  for (int i = 0; i < n; ++i) scanf("%lld%lld", &c[i], &v[i]);
  for (int i = 0; i < k; ++i) scanf("%lld", &g[i]);
  g[k] = 0;
  g[k + 1] = s;
  sort(g, g + k + 2);
  for (int i = 0; i < k + 1; ++i) d.push_back(g[i + 1] - g[i]);
  sort(d.begin(), d.end());
  cum[0] = d[0];
  for (int i = 1; i < int((d).size()); ++i) cum[i] = cum[i - 1] + d[i];
  for (int i = 0; i < n; ++i) {
    if (v[i] >= d[0]) {
      if (v[i] <= 2 * d[0])
        val = 3 * cum[int((d).size()) - 1] - (int((d).size()) - 1) * v[i];
      else {
        x = upper_bound(d.begin(), d.end(), v[i] / 2) - d.begin();
        if (x == int((d).size()))
          val = cum[int((d).size()) - 1];
        else
          val = 3 * cum[int((d).size()) - 1] - 2 * cum[x - 1] -
                (int((d).size()) - x) * v[i];
      }
      if (val <= t) ans = min(ans, c[i]);
    }
  }
  if (ans == 1000000007)
    printf("-1\n");
  else
    printf("%lld\n", ans);
  return 0;
}
