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 n, k, s, t;
pair<int, int> cars[200111];
int g[200111];
long long mustacc;
int distances[200111];
int L = 0;
bool Okay(int capacity) {
  int i;
  long long speed = 0;
  for (i = 1; i <= L; i++) {
    if (distances[i] > capacity) return false;
    if ((long long)capacity >= (long long)distances[i] * 2LL) {
      speed += (long long)distances[i];
    } else {
      speed += (long long)(capacity - distances[i]);
    }
  }
  if (speed >= mustacc)
    return true;
  else
    return false;
}
int main() {
  int i, j;
  int last = 0;
  long long toadd;
  long long largest;
  int l, r, mid, best;
  int mincost;
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (i = 1; i <= n; i++) {
    scanf("%d %d", &cars[i].first, &cars[i].second);
  }
  for (i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g + 1, g + 1 + k);
  g[0] = 0;
  g[k + 1] = s;
  for (i = 1; i <= k + 1; i++) {
    L++;
    distances[L] = g[i] - g[i - 1];
  }
  mustacc = (long long)2 * s - (long long)t;
  l = 1;
  r = 1000000000;
  best = -1;
  while (l <= r) {
    mid = (l + r) / 2;
    if (Okay(mid)) {
      best = mid;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  if (best == -1) {
    printf("-1\n");
    return 0;
  }
  mincost = -1;
  for (i = 1; i <= n; i++) {
    if (cars[i].second >= best) {
      if (mincost == -1 || mincost > cars[i].first) {
        mincost = cars[i].first;
      }
    }
  }
  if (mincost == -1) {
    printf("-1\n");
    return 0;
  }
  printf("%d\n", mincost);
  return 0;
}
