#include <bits/stdc++.h>
const int N = 200200;
using namespace std;
int n, k, s, t;
int c[N];
int v[N];
vector<int> g;
bool f(int x) {
  long long cnt = s + s;
  for (int i = 0; i + 1 < g.size(); i++) {
    if (g[i + 1] - g[i] > x) return false;
    int l = x - (g[i + 1] - g[i]);
    cnt -= min(g[i + 1] - g[i], l);
  }
  return cnt <= t;
}
int main() {
  ios_base::sync_with_stdio(0);
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) scanf("%d%d", &c[i], &v[i]);
  g.push_back(0);
  g.push_back(s);
  for (int i = 1; i <= k; i++) {
    int x;
    scanf("%d", &x);
    g.push_back(x);
  }
  sort(g.begin(), g.end());
  int l = 0, r = 1e9 + 1;
  while (l < r) {
    int m = (l + r) / 2;
    if (f(m))
      r = m;
    else
      l = m + 1;
  }
  int ans = 1e9 + 1;
  for (int i = 1; i <= n; i++)
    if (v[i] >= l) ans = min(ans, c[i]);
  if (ans == 1e9 + 1) ans = -1;
  printf("%d\n", ans);
}
