1 1 2 2
1000000000 1000000000
1
 1 1 1000000000 1000000000
100 1000000000
1
 1 1 10 18
5 6
5
 2 1 1000000000 2000000000
111 999999999
101 999999998
1
 4 13 400 600
13 30
1 19
1 160
1 113
58 73 15 319 194 362 128 157 336 162 77 90 96
 1 15 100 200
283 8
30 58 16 45 80 82 55 95 24 23 86 28 51 47 20
 3 2 300 400
24 68
13 65
15 113
127 177
 1 1 2 1
1 10
1
 4 2 7 15
10 9
4 4
9 3
4 10
1 6
 2 1 1000000000 2000000000
111 1000000000
101 1000000000
5
 2 1 1000000000 2000000000
111 999999998
101 999999998
1
 1 1 1000000000 1000000000
1 1000000000
1

1000000000
 -1
 5
 111
 1
 -1
 -1
 -1
 4
 101
 -1
 -1

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 200005;
int N, K, S, T;
int C[MAXN];
int V[MAXN];
int pos[MAXN];
bool check(int maxCap, int reg, int fast) {
  for (int i = 1; i <= K + 1; i++) {
    int cap = maxCap;
    int dist = pos[i] - pos[i - 1];
    if (cap < dist) return false;
    int a = min(cap / 2, min(cap - dist, fast));
    fast -= a;
    cap -= 2 * a;
    dist -= a;
    int b = min(dist, min(cap, reg));
    reg -= b;
    cap -= b;
    dist -= b;
    if (dist != 0) return false;
  }
  return true;
}
int main() {
  ios::sync_with_stdio(0);
  cin >> N >> K >> S >> T;
  for (int i = 0; i < N; i++) cin >> C[i] >> V[i];
  for (int i = 1; i <= K; i++) cin >> pos[i];
  pos[K + 1] = S;
  sort(pos + 1, pos + K + 1);
  if (T < S) {
    cout << "-1\n";
    return 0;
  }
  int lo = 0, hi = 1000000001;
  while (lo < hi) {
    int mid = lo + (hi - lo) / 2;
    if (check(mid, T - S, 2 * S - T))
      hi = mid;
    else
      lo = mid + 1;
  }
  int best = 1 << 30;
  for (int i = 0; i < N; i++)
    if (V[i] >= lo) best = min(best, C[i]);
  if (best == (1 << 30))
    cout << "-1\n";
  else
    cout << best << "\n";
  return 0;
}
