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 maxN = 200002, INF = 2000000001;
pair<int, int> cars[maxN];
int k, gas[maxN];
int min_time(int cap) {
  int t = 0;
  for (int i = 0; i <= k; i++) {
    int d = gas[i + 1] - gas[i];
    if (cap < d) return INF;
    t += (cap >= d * 2 ? d : d * 2 - (cap % d));
  }
  return t;
}
int main() {
  int n, s, t;
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%d%d", &cars[i].first, &cars[i].second);
  for (int i = 1; i <= k; i++) scanf("%d", gas + i);
  sort(gas, gas + k + 1);
  gas[k + 1] = s;
  int begin = 0, end = s * 2 + 1;
  while (end - begin > 1) {
    int middle = (begin + end) / 2;
    min_time(middle) <= t ? end = middle : begin = middle;
  }
  if (end == s * 2 + 1) {
    printf("-1\n");
    return 0;
  }
  int res = INF;
  for (int i = 0; i < n; i++) {
    if (cars[i].second >= end) res = min(res, cars[i].first);
  }
  printf("%d\n", (res == INF ? -1 : res));
  return 0;
}
