#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2e5 * 5;
struct node {
  int c, v;
} sv[MAXN];
bool cmp1(const node &a, const node &b) { return a.v < b.v; }
bool cmp2(const node &a, const node &b) { return a.c < b.c; }
int g[MAXN];
long long n, k, s, t;
bool judge(long long v) {
  long long tot = 0, tmp;
  for (int i = k; i >= 1; i--) {
    tmp = v;
    long long dis = g[i] - g[i - 1];
    if (dis > v) return false;
    tmp -= dis;
    tot += 2 * dis;
    tot -= min(tmp, dis);
  }
  return tot <= t;
}
int main() {
  scanf("%lld%lld%lld%lld", &n, &k, &s, &t);
  for (int i = 1; i <= n; i++) {
    scanf("%d%d", &sv[i].c, &sv[i].v);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%d", &g[i]);
  }
  k++;
  g[0] = 0, g[k] = s;
  sort(g + 1, g + 1 + k);
  long long l = 0, r = 1e9 + 7, ans = 1e9 + 7;
  while (l <= r) {
    long long m = (l + r) >> 1;
    if (judge(m)) {
      ans = min(ans, m);
      r = m - 1;
    } else {
      l = m + 1;
    }
  }
  node T;
  T.c = 0, T.v = ans;
  sort(sv + 1, sv + 1 + n, cmp1);
  int pos = lower_bound(sv + 1, sv + 1 + n, T, cmp1) - sv;
  sort(sv + pos, sv + 1 + n, cmp2);
  if (pos == n + 1) return 0 * printf("-1\n");
  printf("%d\n", sv[pos].c);
  return 0;
}
