#include <bits/stdc++.h>
using namespace std;
template <typename t>
t read() {
  t x = 0;
  int f = 1, c = getchar();
  while (c > '9' || c < '0') f = c == '-' ? -1 : 1, c = getchar();
  while (c >= '0' && c <= '9') x = x * 10 + c - 48, c = getchar();
  return x * f;
}
template <typename t>
void write(t x) {
  if (x < 0) {
    putchar('-'), write(-x);
    return;
  }
  if (x >= 10) write(x / 10);
  putchar(x % 10 + 48);
}
const int maxn = 2e5 + 10;
const int maxv = 1e9 + 10;
struct Car {
  int c, v;
} car[maxn];
int n, k, s, t, g[maxn], mxg, mxv, ans;
bool jud(int x) {
  if (x < mxg) return 0;
  int tot = 0;
  for (int i = 1; i <= k + 1; i++) {
    tot += max(g[i] * 3 - x, g[i]);
    if (tot > t) return 0;
  }
  return 1;
}
int main() {
  n = read<int>(), k = read<int>(), s = read<int>(), t = read<int>();
  for (int i = 1; i <= n; i++) car[i].c = read<int>(), car[i].v = read<int>();
  for (int i = 1; i <= k; i++) g[i] = read<int>();
  sort(g + 1, g + k + 1);
  g[k + 1] = s;
  for (int i = k + 1; i >= 1; i--) mxg = max(mxg, g[i] -= g[i - 1]);
  mxv = maxv;
  for (int l = 0, r = maxv, m; l <= r;
       jud(m = l + r >> 1) ? r = m - 1, mxv = m : l = m + 1)
    ;
  ans = maxv;
  for (int i = 1; i <= n; i++)
    if (car[i].v >= mxv) ans = min(ans, car[i].c);
  ans = (ans == maxv || mxv == maxv) ? -1 : ans;
  write(ans);
  return 0;
}
