#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 18;
int n, k, s, t, c[N], v[N], p[N];
bool judge(int c) {
  int sum = 0;
  for (int i = 1; i <= k; i++) {
    int d = p[i] - p[i - 1];
    if (d > c) return 0;
    sum += d + max(d + d - c, 0);
  }
  return sum <= t;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) scanf("%d%d", v + i, c + i);
  for (int i = 1; i <= k; i++) scanf("%d", p + i);
  p[++k] = s, sort(p + 1, p + k + 1);
  int L = 1, R = 1 << 30;
  for (; L < R;) {
    int mid = (L + R) >> 1;
    if (judge(mid))
      R = mid;
    else
      L = mid + 1;
  }
  if (!judge(L))
    puts("-1");
  else {
    int res = (1 << 30);
    for (int i = 1; i <= n; i++)
      if (c[i] >= L) res = min(res, v[i]);
    if (res == 1 << 30)
      puts("-1");
    else
      cout << res << endl;
  }
}
