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;
pair<int, int> vc[200010];
int gas[200010];
int n, k, s, t;
int excess;
bool sort_cmp(pair<int, int> a, pair<int, int> b) {
  if (a.second != b.second) return a.second < b.second;
  return a.first < b.first;
}
bool can(int idx) {
  int curexcess = excess;
  for (int i = 0; i <= k; i++) {
    int jarak;
    if (!i) {
      jarak = gas[0];
    } else if (i == k) {
      jarak = s - gas[k - 1];
    } else {
      jarak = gas[i] - gas[i - 1];
    }
    int lebih = vc[idx].first - jarak;
    if (lebih < 0) return false;
    curexcess -= min(curexcess, min(lebih, jarak));
  }
  if (curexcess > 0) return false;
  return true;
}
int main(void) {
  scanf("%d", &n);
  scanf("%d", &k);
  scanf("%d", &s);
  scanf("%d", &t);
  for (int i = 0; i < n; i++) {
    scanf("%d", &vc[i].second);
    scanf("%d", &vc[i].first);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", &gas[i]);
  }
  excess = max(0, s * 2 - t);
  sort(gas, gas + k);
  sort(vc, vc + n);
  int lo, hi;
  lo = 0;
  hi = n - 1;
  while (lo < hi) {
    int mid = lo + (hi - lo) / 2;
    if (can(mid)) {
      hi = mid;
    } else {
      lo = mid + 1;
    }
  }
  if (!can(lo)) {
    printf("-1");
  } else {
    int mini = 1000000000;
    for (int i = lo; i < n; i++) {
      mini = min(mini, vc[i].second);
    }
    printf("%d\n", mini);
  }
  return 0;
}
