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 int64_t N = 1e5;
int64_t n, k, s, t;
vector<int64_t> pos;
bool ch(int64_t w) {
  int64_t ch = 1, time = 0;
  for (int j = 1; j <= k + 1; ++j) {
    int64_t cur = w;
    if (pos[j] - pos[j - 1] > w) {
      ch = 0;
      break;
    } else {
      time += (pos[j] - pos[j - 1]) * 2;
      w -= (pos[j] - pos[j - 1]);
      time -= min(w, pos[j] - pos[j - 1]);
    }
    w = cur;
  }
  if (ch && t >= time) {
    return true;
  } else {
    return false;
  }
}
void solve() {
  cin >> n >> k >> s >> t;
  vector<pair<int64_t, int64_t>> cars(n);
  for (int i = 0; i < n; ++i) {
    cin >> cars[i].first >> cars[i].second;
  }
  pos.push_back(0);
  for (int i = 1; i <= k; ++i) {
    int64_t x;
    cin >> x;
    pos.push_back(x);
  }
  pos.push_back(s);
  sort(pos.begin(), pos.end());
  int64_t l = 0, r = 4 * N;
  while (r - l > 1) {
    int64_t mid = (l + r) / 2;
    if (ch(mid)) {
      r = mid;
    } else {
      l = mid;
    }
  }
  int64_t ans = 4 * N;
  for (int i = 0; i < n; ++i) {
    if (cars[i].second >= r) {
      ans = min(ans, cars[i].first);
    }
  }
  if (ans == 4 * N)
    cout << "-1\n";
  else
    cout << ans << "\n";
}
int main() {
  int64_t R = 1;
  while (R--) {
    solve();
  }
  return 0;
}
