#include <bits/stdc++.h>
using namespace std;
const int MAX_MEM = (int)1e8;
int mpos = 0;
char mem[MAX_MEM];
inline void *operator new(size_t n) {
  char *res = mem + mpos;
  mpos += n;
  return (void *)res;
}
inline void operator delete(void *) {}
struct __io_dev {
  __io_dev(const bool &__fastio = false) {
    if (__fastio) ios_base::sync_with_stdio(false), cin.tie(nullptr);
    srand(time(nullptr));
    if (!string("").empty())
      freopen(
          ""
          ".in",
          "r", stdin),
          freopen(
              ""
              ".out",
              "w", stdout);
  }
  ~__io_dev() { fprintf(stderr, "%.6f ms\n", 1e3 * clock() / CLOCKS_PER_SEC); }
} __io(false);
const long long inf = (long long)1e+9 + 7ll;
const long long linf = (long long)1e+18 + 7ll;
const long double eps = (long double)1e-9;
const long double pi = acosl((long double)-1.0);
const int alph = 26;
const int maxs = 512l;
static char buff[(int)2e6 + 17];
long long __p[3] = {29ll, 31ll, 33ll};
long long __mod[3] = {inf, inf + 2ll, 14881337ll};
const int maxn = (int)3e5 + 17;
int n, k, s, t;
int x[maxn];
pair<int, int> a[maxn];
bool check(int i) {
  int cur = 0, v = a[i].first;
  for (long long i = (long long)1; i < (long long)k; ++i) {
    int l = x[i] - x[i - 1];
    if (v < l) return false;
    cur += min(l, v - l) + 2 * (l - min(l, v - l));
  }
  return cur <= t;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (long long i = 0ll; i < (long long)n; ++i)
    scanf("%d %d", &a[i].second, &a[i].first);
  for (long long i = 0ll; i < (long long)k; ++i) scanf("%d", x + i);
  x[k++] = 0, x[k++] = s;
  sort(x, x + k);
  sort(a, a + n);
  for (int i = n - 2; i >= 0; --i)
    a[i].second = min(a[i].second, a[i + 1].second);
  int l = 0, r = n - 1;
  for (int m; l < r; m = (l + r) / 2, check(m) ? r = m : l = m + 1)
    ;
  if (check(l))
    printf("%d\n", a[l].second);
  else
    printf("-1\n");
  return 0;
}
