#include <bits/stdc++.h>
using namespace std;
int n, k, s, T;
int g[500010];
struct dian {
  int c;
  int v;
} node[500010];
int cmp1(dian a, dian b) { return a.v < b.v; }
int cmp2(dian a, dian b) { return a.c < b.c; }
bool judge(int sum) {
  int t = 0;
  for (int i = 2; i <= k; i++) {
    int dis = g[i] - g[i - 1];
    if (sum < dis) return false;
    if (sum >= 2 * dis)
      t += dis;
    else
      t += 3 * dis - sum;
    if (t > T) return false;
  }
  return true;
}
int main() {
  while (~scanf("%d %d %d %d", &n, &k, &s, &T)) {
    for (int i = 1; i <= n; i++) {
      scanf("%d %d", &node[i].c, &node[i].v);
    }
    for (int i = 1; i <= k; i++) {
      scanf("%d", &g[i]);
    }
    g[++k] = 0;
    g[++k] = s;
    sort(g + 1, g + 1 + k);
    sort(node + 1, node + 1 + n, cmp1);
    int ans = -1;
    int l = 1;
    int r = n;
    while (l <= r) {
      int mid = (l + r) / 2;
      if (judge(node[mid].v)) {
        ans = mid;
        r = mid - 1;
      } else {
        l = mid + 1;
      }
    }
    if (ans == -1) {
      printf("-1\n");
    } else {
      int min = 1000000000;
      for (int i = 1; i <= n; i++) {
        if (node[i].v >= node[ans].v && node[i].c < min) min = node[i].c;
      }
      cout << min << endl;
    }
  }
  return 0;
}
