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 = 2 * 1e5 + 10;
int n, m, len, tim;
struct node {
  int p, w;
} car[N];
int sta[N];
bool judge(int temp) {
  int x = 0, y;
  for (int i = 1; i <= m; i++) {
    y = sta[i] - sta[i - 1];
    if (y > temp) return false;
    x += (y * 2 - (temp - y > y ? y : temp - y));
  }
  y = len - sta[m];
  if (y > temp) return false;
  x += (y * 2 - (temp - y > y ? y : temp - y));
  if (x <= tim) return true;
  return false;
}
int solve(int temp) {
  int ans = 1e9 + 10, s = -1;
  for (int i = 0; i < n; i++)
    if (car[i].w >= temp && car[i].p < ans) {
      ans = car[i].p;
      s = i;
    }
  return s;
}
int main() {
  cin >> n >> m >> len >> tim;
  for (int i = 0; i < n; i++) scanf("%d%d", &car[i].p, &car[i].w);
  for (int i = 1; i <= m; i++) scanf("%d", &sta[i]);
  sta[0] = 0;
  sort(sta + 1, sta + m + 1);
  int high = 1e9 + 1, low = 0;
  while (high > low) {
    int mid = (high + low) >> 1;
    if (judge(mid))
      high = mid;
    else
      low = mid + 1;
  }
  int temp = solve(high);
  printf("%d\n", temp == -1 ? temp : car[temp].p);
  return 0;
}
