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 N = 200010;
int n, m, S, T;
int aa[N], bb[N];
int pos[N];
bool check(int v) {
  int tm = 0;
  for (int i = 1; i <= m; i++) {
    if (pos[i] - pos[i - 1] > v) return false;
    int remain = min(v - (pos[i] - pos[i - 1]), pos[i] - pos[i - 1]);
    tm += (pos[i] - pos[i - 1]) * 2 - remain;
  }
  return tm <= T;
}
int main() {
  scanf("%d%d%d%d", &n, &m, &S, &T);
  for (int i = 1; i <= n; i++) scanf("%d%d", aa + i, bb + i);
  for (int i = 1; i <= m; i++) scanf("%d", pos + i);
  sort(pos + 1, pos + 1 + m);
  pos[++m] = S;
  int lf = 1, rg = 1000000000;
  while (lf < rg) {
    int mid = (lf + rg) >> 1;
    if (check(mid))
      rg = mid;
    else
      lf = mid + 1;
  }
  int ans = -1;
  for (int i = 1; i <= n; i++) {
    if (bb[i] >= lf) {
      if (ans == -1 || ans > aa[i]) ans = aa[i];
    }
  }
  printf("%d\n", ans);
}
