#include <bits/stdc++.h>
using namespace std;
const int P = 1e9 + 7, INF = 0x3f3f3f3f;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long qpow(long long a, long long n) {
  long long r = 1 % P;
  for (a %= P; n; a = a * a % P, n >>= 1)
    if (n & 1) r = r * a % P;
  return r;
}
long long inv(long long first) {
  return first <= 1 ? 1 : inv(P % first) * (P - P / first) % P;
}
const int N = 1e6 + 10;
int n, k, s, t;
int c[N], v[N], a[N], g[N];
int chk(int first) {
  if (g[k] > first) return 0;
  long long sum = 0;
  for (int i = 1; i <= k; ++i) {
    int p = min(g[i], first - g[i]);
    sum += (long long)2 * g[i] - p;
  }
  return sum <= t;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  if (s > t) return puts("-1"), 0;
  for (int i = 1; i <= n; ++i) scanf("%d%d", c + i, v + i);
  for (int i = 1; i <= k; ++i) scanf("%d", a + i);
  a[++k] = 0, a[++k] = s;
  sort(a + 1, a + 1 + k);
  for (int i = 2; i <= k; ++i) g[i - 1] = a[i] - a[i - 1];
  --k;
  sort(g + 1, g + 1 + k);
  int l = 1, r = 1e9, ans = INF;
  while (l <= r) {
    if (chk(((l + r) >> 1)))
      ans = ((l + r) >> 1), r = ((l + r) >> 1) - 1;
    else
      l = ((l + r) >> 1) + 1;
  }
  int mi = INF;
  for (int i = 1; i <= n; ++i)
    if (v[i] >= ans) mi = min(mi, c[i]);
  printf("%d\n", mi == INF ? -1 : mi);
}
