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 pos[200005];
struct lx {
  int cost, val;
} num[200005];
vector<int> vec;
int n, k, s, t, temp[200005], last = 0, maxn = 0, m2 = 0;
int Bsearch(int L, int R) {
  int mid, l = L, r = R, co;
  while (l < r) {
    co = 0;
    mid = (l + r) / 2;
    for (int i = 0; i < vec.size(); ++i) {
      co += vec[i] * 2 - min(vec[i], mid - vec[i]);
    }
    if (co <= t) {
      r = mid;
    } else {
      l = mid + 1;
    }
  }
  return l;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; ++i) {
    scanf("%d%d", &num[i].cost, &num[i].val);
    m2 = max(m2, num[i].val);
  }
  for (int i = 0; i < k; ++i) {
    scanf("%d", &temp[i]);
  }
  sort(temp, temp + k);
  for (int i = 0; i < k; ++i) {
    vec.push_back(temp[i] - last);
    maxn = max(maxn, temp[i] - last);
    last = temp[i];
  }
  vec.push_back(s - last);
  maxn = max(maxn, s - last);
  if (s > t) {
    printf("-1\n");
    return 0;
  }
  int co = 0;
  for (int i = 0; i < vec.size(); ++i) {
    co += vec[i] * 2 - min(vec[i], m2 - vec[i]);
  }
  if (co > t) {
    printf("-1\n");
    return 0;
  }
  int minn = Bsearch(maxn, maxn * 2), ans = 0x3f3f3f3f;
  for (int i = 0; i < n; ++i) {
    if (num[i].val >= minn) {
      ans = min(ans, num[i].cost);
    }
  }
  if (ans == 0x3f3f3f3f)
    printf("-1\n");
  else
    printf("%d\n", ans);
}
