#include <bits/stdc++.h>
using namespace std;
const int N = 200100;
const int INF = 0x63636363;
int n, k, s, t;
int c[N], v[N];
int g[N];
bool ok(int fuel) {
  int pos = 0;
  long long total_time = 0;
  for (int i = 0; i <= k; i++) {
    if (g[i] - pos > fuel) {
      return false;
    }
    if (fuel >= 2 * (g[i] - pos)) {
      total_time += g[i] - pos;
    } else {
      long long rem = fuel % (g[i] - pos);
      total_time += rem + 2 * (g[i] - pos - rem);
    }
    pos = g[i];
  }
  return total_time <= t;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  vector<int> tanks;
  for (int i = 0; i < n; i++) {
    scanf("%d%d", &c[i], &v[i]);
    tanks.push_back(v[i]);
  }
  for (int i = 0; i < k; i++) {
    scanf("%d", &g[i]);
  }
  sort(g, g + k);
  g[k] = s;
  sort(tanks.begin(), tanks.end());
  int begin = 0, end = tanks.size() - 1;
  if (ok(tanks[end])) {
    while (begin != end) {
      int mid = (begin + end) / 2;
      if (ok(tanks[mid])) {
        end = mid;
      } else {
        begin = mid + 1;
      }
    }
    int minimum = INF;
    for (int i = 0; i < n; i++) {
      if (v[i] >= tanks[begin] && c[i] < minimum) {
        minimum = c[i];
      }
    }
    printf("%d\n", minimum == INF ? -1 : minimum);
  } else {
    printf("-1\n");
  }
  return 0;
}
