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;
int cost[200005], volume[200005], Point[200005];
int n, k, s, t;
inline bool Ok(int V) {
  int time = 0, i;
  for (i = 1; i < k; ++i) {
    int d = Point[i + 1] - Point[i];
    int x = min(V - d, d);
    time += 2 * d - x;
  }
  return (time <= t);
}
int main() {
  int i;
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; ++i) scanf("%d%d", &cost[i], &volume[i]);
  Point[1] = 0;
  for (i = 2; i <= k + 1; ++i) scanf("%d", &Point[i]);
  Point[k + 2] = s;
  k += 2;
  sort(Point + 1, Point + k + 1);
  int st = 0, dr = 2000000000, mij, sol;
  for (i = 1; i < k; ++i) st = max(st, Point[i + 1] - Point[i]);
  while (st <= dr) {
    mij = ((st + dr) >> 1);
    if (Ok(mij)) {
      sol = mij;
      dr = mij - 1;
    } else
      st = mij + 1;
  }
  int ans = 2000000000;
  for (i = 1; i <= n; ++i)
    if (volume[i] >= sol) ans = min(ans, cost[i]);
  if (ans == 2000000000)
    printf("-1\n");
  else
    printf("%d\n", ans);
  return 0;
}
