#include <bits/stdc++.h>
using namespace std;
int dx[] = {-1, 1, 0, 0};
int dy[] = {0, 0, -1, 1};
int n, k, s, t, c[200010], v[200010], g[200010], sum[200010];
vector<int> l;
bool check(int V) {
  if (V < l.back()) return false;
  auto it = upper_bound(l.begin(), l.end(), V / 2);
  int cost = 0;
  if (it != l.end()) {
    int pos = it - l.begin();
    int len = s - sum[pos];
    cost += 3 * len - V * (int((l).size()) - pos);
    cost += sum[pos];
  } else {
    cost = s;
  }
  return cost <= t;
}
int solve() {
  sort((l).begin(), (l).end());
  for (int i = 1; i < int((l).size()); i++) sum[i] = sum[i - 1] + l[i - 1];
  int ans = -1;
  for (int i = 0; i < n; i++) {
    if (check(v[i])) ans = ans == -1 ? c[i] : min(ans, c[i]);
  }
  return ans;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%d%d", &c[i], &v[i]);
  for (int i = 1; i <= k; i++) scanf("%d", &g[i]);
  sort(g + 1, g + 1 + k);
  for (int i = 1; i <= k; i++) l.push_back(g[i] - g[i - 1]);
  l.push_back(s - g[k]);
  printf("%d\n", solve());
  return 0;
}
