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;
int N, K, S, T;
int C[201010], V[201010], G[201010];
bool check(int f) {
  long long t = 0;
  int pre = 0;
  for (int i = 0; i < K; i++) {
    int d = G[i] - pre;
    if (f < d) return false;
    t += d * 2LL;
    int fd = f - d;
    t -= min(d, fd);
    if (T < t) return false;
    pre = G[i];
  }
  return true;
}
int main() {
  cin >> N >> K >> S >> T;
  for (int i = 0; i < N; i++) scanf("%d %d", &C[i], &V[i]);
  for (int i = 0; i < K; i++) scanf("%d", &G[i]);
  G[K] = S;
  K++;
  sort(G, G + K);
  int l = 0, r = INT_MAX / 2;
  while (l + 1 != r) {
    int c = (l + r) / 2;
    if (check(c))
      r = c;
    else
      l = c;
  }
  int ans = INT_MAX / 2;
  for (int i = 0; i < N; i++) {
    if (r <= V[i]) ans = min(ans, C[i]);
  }
  if (ans == INT_MAX / 2) ans = -1;
  cout << ans << endl;
}
