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;
long long c[200007], l[200007], z[200007], p[200007];
int main() {
  long long n, k, s, t, i, kol, L, M, R, time, ans = INT_MAX;
  bool OK;
  cin >> n >> k >> s >> t;
  for (i = 1; i <= n; i++) cin >> c[i] >> l[i];
  for (i = 1; i <= k; i++) cin >> z[i];
  z[0] = 0;
  z[k + 1] = s;
  sort(z + 1, z + k + 1);
  kol = t - s;
  if (kol < 0) {
    cout << -1;
    return 0;
  }
  L = 0;
  R = 1000000000;
  while (R - L > 1) {
    M = (R + L) / 2;
    time = 0;
    OK = true;
    for (i = 1; i <= k + 1; i++)
      if (z[i] - z[i - 1] > M) {
        L = M;
        OK = false;
        break;
      } else {
        kol = M - (z[i] - z[i - 1]);
        if (kol >= z[i] - z[i - 1])
          time += z[i] - z[i - 1];
        else
          time += (kol + (z[i] - z[i - 1] - kol) * 2);
      }
    if (OK) {
      if (time <= t)
        R = M;
      else
        L = M;
    }
  }
  for (i = 1; i <= n; i++)
    if (l[i] >= R) ans = min(ans, c[i]);
  if (ans != INT_MAX)
    cout << ans;
  else
    cout << -1;
}
