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;
struct car {
  int c, v;
  car() {}
  car(int _c, int _v) : c(_c), v(_v) {}
};
int main() {
  int n, k, s, t;
  cin >> n >> k >> s >> t;
  vector<car> a(n);
  for (int i = 0, c, v; i < n; ++i) {
    cin >> c >> v;
    a[i] = car(c, v);
  }
  vector<int> gas(k);
  for (int i = 0; i < k; ++i) {
    cin >> gas[i];
  }
  sort(gas.begin(), gas.end());
  int curr = 0;
  int maxlen = 0;
  for (int i = 0; i < k; ++i) {
    maxlen = max(maxlen, gas[i] - curr);
    curr = gas[i];
  }
  maxlen = max(maxlen, s - gas[k - 1]);
  int besttime = 2 * 1000000000 + 5;
  int ans = 2000000000;
  for (int i = 0; i < n; ++i) {
    if (a[i].v < maxlen) continue;
    int diff = a[i].v - maxlen;
    int r = diff + (maxlen - diff) * 2;
    r += 2 * (s - maxlen);
    if (besttime >= r) {
      besttime = r;
      ans = min(ans, a[i].c);
    }
  }
  if (ans == 2000000000) ans = -1;
  cout << ans << endl;
  return 0;
}
