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 INF = 0x3f3f3f3f;
const long long LLINF = 0x3f3f3f3f3f3f3f3f;
struct lt {
  long long a, b, c;
  lt() {}
  lt(long long _a, long long _b, long long _c) {
    a = _a;
    b = _b;
    c = _c;
  }
  bool operator<(lt d) const { return b > d.b; }
};
int a[200200][2];
int wori[200200];
int main() {
  int n, m, s, t;
  scanf("%d%d%d%d", &n, &m, &s, &t);
  for (int i = 0; i < n; ++i) scanf("%d%d", &a[i][0], &a[i][1]);
  int now = 0;
  priority_queue<lt> q;
  for (int i = 0; i < m; ++i) scanf("%d", wori + i);
  wori[m] = s;
  sort(wori, wori + m + 1);
  for (int i = 0; i <= m; ++i) {
    q.push(lt(2 * (wori[i] - now), wori[i] - now, wori[i] - now));
    now = wori[i];
  }
  long long xq = s * 2LL - t;
  for (int i = 0; i < xq; ++i) {
    lt b = q.top();
    q.pop();
    now = max((long long)now, b.b);
    if (b.a > b.c) {
      b.a -= 1;
      b.b += 1;
      q.push(b);
    } else
      --i;
  }
  while (!q.empty()) now = q.top().b, q.pop();
  int ans = INF;
  for (int i = 0; i < n; ++i)
    if (a[i][1] >= now) ans = min(ans, a[i][0]);
  printf("%d\n", ans);
  return 0;
}
