#include <bits/stdc++.h>
using namespace std;
inline void in(int &a) { scanf("%d", &a); }
const int MAX = 2e5 + 5;
pair<int, int> cars[MAX];
int gas[MAX];
int n, k, s, t;
bool check(int fuelTank, int time) {
  int currTime = 0;
  for (int i = 1; i < k + 2; i++) {
    int now = gas[i] - gas[i - 1];
    if (fuelTank < now) return false;
    int a = fuelTank - now;
    int b = 2 * now - fuelTank;
    if (b < 0) {
      a = now;
      b = 0;
    }
    currTime += a + 2 * b;
  }
  return currTime <= time;
}
int main() {
  scanf("%d %d %d %d", &n, &k, &s, &t);
  for (int i = 0; i < n; i++) scanf("%d %d", &cars[i].first, &cars[i].second);
  for (int i = 1; i < k + 1; i++) scanf("%d", &gas[i]);
  sort(gas + 1, gas + k + 1);
  gas[k + 1] = s;
  if (t < s) {
    puts("-1");
    return 0;
  }
  int left = 0, right = s, curr, ans = 3 * s - t;
  while (left <= right) {
    curr = (left + right) >> 1;
    if (check(curr, t)) {
      ans = curr;
      right = curr - 1;
    } else {
      left = curr + 1;
    }
  }
  int mn = INT32_MAX;
  for (int i = 0; i < n; i++) {
    if (cars[i].second >= ans) {
      mn = min(mn, cars[i].first);
    }
  }
  puts(mn == INT32_MAX ? "-1" : to_string(mn).c_str());
  return 0;
}
