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 = 1e15;
struct node {
  long long val, v;
} w[100010];
long long a[100010];
int n, m, S, T;
bool check(long long x) {
  int t = 0;
  for (int i = 1; i <= m; i++) {
    long long d = a[i] - a[i - 1];
    if (d > x) return false;
    if (2 * d <= x) {
      t += d;
    } else {
      t += 3 * d - x;
    }
    if (t > T) return false;
  }
  return true;
}
int main() {
  scanf("%d%d%d%d", &n, &m, &S, &T);
  for (int i = 1; i <= n; i++) {
    scanf("%lld%lld", &w[i].val, &w[i].v);
  }
  for (int i = 1; i <= m; i++) {
    scanf("%lld", &a[i]);
  }
  a[++m] = S;
  sort(a + 1, a + m + 1);
  long long l = 0, r = 2 * S;
  long long maxn = -1, ans = inf;
  while (l < r) {
    long long mid = (l + r) / 2;
    if (check(mid)) {
      maxn = mid;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  if (maxn == -1) {
    printf("-1\n");
  } else {
    for (int i = 1; i <= n; i++) {
      if (w[i].v >= maxn) {
        ans = min(ans, w[i].val);
      }
    }
    if (ans == inf) {
      printf("-1\n");
    } else {
      printf("%lld\n", ans);
    }
  }
  return 0;
}
