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 = 200100;
const long long INF = (long long)3e9;
int n, k, s, t;
long long v[N], c[N], g[N];
long long calc(long long len, long long cap) {
  if (cap < len) {
    return INF;
  }
  long long y = min(len, cap - len);
  long long x = len - y;
  return x + x + y;
}
bool check(int mid) {
  long long sum = 0;
  long long cap = 0;
  for (int i = 0; i < n; i++) {
    if (c[i] <= mid) {
      cap = max(cap, v[i]);
    }
  }
  for (int i = 0; i <= k; i++) {
    sum += calc(g[i + 1] - g[i], cap);
  }
  return sum <= t;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) {
    scanf("%lld %lld", &c[i], &v[i]);
  }
  g[0] = 0;
  for (int i = 1; i <= k; i++) {
    scanf("%lld", &g[i]);
  }
  g[k + 1] = s;
  sort(g, g + (k + 1));
  int low = 0;
  int high = *max_element(c, c + n);
  if (!check(high)) {
    puts("-1");
    exit(0);
  }
  while (low <= high) {
    int mid = (low + high) / 2;
    if (check(mid)) {
      high = mid - 1;
    } else {
      low = mid + 1;
    }
  }
  printf("%d\n", low);
  return 0;
}
