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;
int g[500010];
struct dian {
  int c;
  int v;
};
dian NODE[500010];
dian node[500010];
int cmp(dian a, dian b) {
  if (a.c != b.c)
    return a.c < b.c;
  else
    return a.v > b.v;
}
int func(int num) {
  int t = 0;
  for (int i = 1; i < k; i++) {
    int dis = g[i] - g[i - 1];
    if (node[num].v >= 2 * dis)
      t += dis;
    else
      t += 3 * dis - node[num].v;
  }
  return t;
}
int erfen(int num) {
  int l = 1;
  int r = num;
  while (l != r) {
    int mid = (l + r) / 2;
    if (func(mid) == T)
      return node[mid].c;
    else if (func(mid) < T)
      r = mid;
    else
      l = mid + 1;
  }
  return node[l].c;
}
int main() {
  while (~scanf("%d %d %d %d", &n, &k, &s, &T)) {
    for (int i = 0; i < n; i++) {
      scanf("%d %d", &NODE[i].c, &NODE[i].v);
    }
    for (int i = 0; i < k; i++) {
      scanf("%d", &g[i]);
    }
    g[k++] = 0;
    g[k++] = s;
    sort(g, g + k);
    int maxdis = 0;
    for (int i = 1; i < k; i++) {
      maxdis = max(maxdis, g[i] - g[i - 1]);
    }
    sort(NODE, NODE + n, cmp);
    int lastc = 0;
    int lastv = 0;
    int num = 0;
    for (int i = 0; i < n; i++) {
      if (NODE[i].v >= maxdis) {
        if (NODE[i].c > lastc && NODE[i].v > lastv) {
          lastc = NODE[i].c;
          lastv = NODE[i].v;
          node[++num] = NODE[i];
        }
      }
    }
    if (!num || func(num) > T)
      printf("-1\n");
    else
      printf("%d\n", erfen(num));
  }
  return 0;
}
