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 int MOD = 1e9 + 7;
const int INF = 1e9 + 5;
const long long INF64 = 1e18;
template <typename T>
string to_string(const vector<T> &v) {
  string ret = "<";
  for (auto it : v) {
    ret += to_string(it) + ", ";
  }
  ret.pop_back();
  ret.pop_back();
  ret += ">";
  return ret;
}
void debug_print() { cerr << endl; }
template <typename T, typename... U>
void debug_print(T t, U... u) {
  cerr << " " << to_string(t);
  debug_print(u...);
}
const int N = 1e5 + 5;
vector<pair<long long, long long> > v;
vector<long long> fuel;
bool can(long long cur, long long t) {
  long long now = 0ll;
  for (int i = 0; i < fuel.size(); i++) {
    if (fuel[i] > cur) return false;
    long long x = (cur - fuel[i]);
    long long y = 2 * fuel[i] - 2 * x;
    if (y < 0) {
      x = fuel[i];
      y = 0;
    }
    now += x + y;
  }
  return now <= t;
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0);
  long long n, k, s, t;
  cin >> n >> k >> s >> t;
  v.resize(n);
  for (auto &it : v) {
    cin >> it.first >> it.second;
  }
  vector<long long> pos;
  for (int i = 0; i < k; i++) {
    long long a;
    cin >> a;
    pos.push_back(a);
  }
  sort(pos.begin(), pos.end());
  for (int i = 0; i < k; i++) {
    if (i == 0)
      fuel.push_back(pos[i]);
    else
      fuel.push_back(pos[i] - pos[i - 1]);
  }
  fuel.push_back(s - pos.back());
  long long lo = 0;
  long long hi = INF;
  while (lo < hi) {
    long long mid = lo + (hi - lo) / 2;
    if (can(mid, t)) {
      hi = mid;
    } else
      lo = mid + 1;
  }
  long long ans = INF64;
  for (auto it : v) {
    if (it.second < hi) continue;
    ans = min(ans, it.first);
  }
  cout << (ans == INF64 ? -1 : ans) << endl;
  return 0;
}
