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;
vector<pair<long long, long long>> c;
vector<pair<long long, long long>> cars;
vector<long long> gas;
vector<long long> dist;
long n, k;
long long s, T;
bool can(long mid) {
  long long t = 0;
  for (auto d : dist) {
    long long temp = min(d, cars[mid].second - d);
    if (temp < 0) return false;
    t += temp + (d - temp) * 2;
  }
  return t <= T;
}
int main() {
  scanf("%d%d%I64d%I64d", &n, &k, &s, &T);
  long long x, y;
  for (int i = 0; i < n; ++i) {
    scanf("%I64d%I64d", &x, &y);
    c.push_back(make_pair(x, y));
  }
  sort(begin(c), end(c));
  cars.push_back(c[0]);
  for (int i = 1; i < c.size(); ++i)
    if (c[0].second < c[i].second) cars.push_back(c[i]);
  for (int i = 0; i < k; ++i) {
    scanf("%I64d", &x);
    gas.push_back(x);
  }
  gas.push_back(0);
  gas.push_back(s);
  sort(begin(gas), end(gas));
  for (int i = 1; i < gas.size(); ++i) dist.push_back(gas[i] - gas[i - 1]);
  long ans = -1;
  long l = 0, r = cars.size();
  while (l < r) {
    long mid = (l + r) / 2;
    if (can(mid)) {
      ans = mid;
      r = mid;
    } else
      l = mid + 1;
  }
  if (ans == -1)
    puts("-1");
  else
    printf("%I64d", cars[ans].first);
}
