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;
long long n, gas, lis[200005], s, t, cost, cap;
pair<long long, long long> p[200005];
vector<pair<long long, long long> > v;
bool check(int x) {
  cap = v[x].second;
  long long tot = 0;
  for (int i = (0); i <= (gas); i++) {
    long long tmp = lis[i + 1] - lis[i];
    if (tmp > cap) return false;
    tot += tmp * 2;
    tot -= min(tmp, cap - tmp);
  }
  return tot <= t;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> n >> gas >> s >> t;
  for (int i = (0); i <= ((n)-1); i++) {
    cin >> cost >> cap;
    p[i] = {cost, cap};
  }
  for (int i = (1); i <= (gas); i++) cin >> lis[i];
  sort(lis + 1, lis + 1 + gas);
  lis[gas + 1] = s;
  sort(p, p + n);
  v.push_back(p[0]);
  for (int i = (1); i <= (n - 1); i++) {
    cost = v.back().first;
    cap = v.back().second;
    if (p[i].second < cap) continue;
    if (p[i].first == cost) {
      v.pop_back();
    }
    v.push_back(p[i]);
  }
  int high = v.size();
  int low = 0;
  while (high > low) {
    int chs = (high + low) / 2;
    if (check(chs))
      high = chs;
    else
      low = chs + 1;
  }
  if (high == v.size())
    cout << -1;
  else
    cout << v[high].first;
}
