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 = 2e9 + 5;
const int N = 2e5 + 5;
int c[N], v[N], g[N];
int n, k, s, t;
int check(int vv) {
  int ans = 0;
  for (int i = 1; i <= k + 1; i++) {
    int gap = g[i] - g[i - 1];
    if (gap > vv) return INF;
    ans += gap * 2LL <= vv ? gap : 3LL * gap - vv;
  }
  return ans;
}
int main() {
  while (scanf("%d%d%d%d", &n, &k, &s, &t) == 4) {
    for (int i = 1; i <= n; i++) {
      scanf("%d%d", c + i, v + i);
    }
    for (int i = 1; i <= k; i++) {
      scanf("%d", g + i);
    }
    sort(g + 1, g + k + 1);
    g[k + 1] = s;
    int l = 0, r = 1e9 + 5, tar = -1;
    while (l <= r) {
      int mid = (l + r) / 2;
      if (check(mid) <= t) {
        tar = mid;
        r = mid - 1;
      } else {
        l = mid + 1;
      }
    }
    int pos = -1;
    for (int i = 1; i <= n; i++) {
      if (v[i] >= tar) {
        if (pos == -1 || c[i] < c[pos] || (c[i] == c[pos] && v[i] > v[pos])) {
          pos = i;
        }
      }
    }
    if (pos == -1) {
      puts("-1");
    } else {
      printf("%d\n", c[pos]);
    }
  }
  return 0;
}
