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 = 2e5 + 7;
int n, k;
long long int s, t;
long long int g[N];
long long int ic[N], iv[N];
bool solve(long long int c) {
  long long int tt = 0;
  for (int i = 1; i <= k; i++) {
    long long int d = g[i] - g[i - 1];
    long long int a = min(d, c - d);
    if (a < 0) return false;
    tt += d + d - a;
    if (tt > t) return false;
  }
  return (tt <= t);
}
int main() {
  scanf("%d %d %lld %lld", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%lld %lld", &iv[i], &ic[i]);
  for (int i = 1; i <= k; i++) scanf("%lld", &g[i]);
  k++;
  g[k] = s;
  sort(g, g + k + 1);
  long long int lo = 0;
  long long int hi = 1e9 + 3;
  while (lo < hi) {
    long long int mid = (lo + hi) / 2;
    if (solve(mid))
      hi = mid;
    else
      lo = mid + 1;
  }
  long long int res = 1e9 + 3;
  for (int i = 0; i < n; i++) {
    if (ic[i] >= lo) res = min(iv[i], res);
  }
  if (res == 1e9 + 3) res = -1;
  printf("%lld\n", res);
}
