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 main() {
  long long n, k, s, t, c, v;
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cin >> n >> k >> s >> t;
  vector<pair<long long, long long> > cars(n);
  for (long long i = 0; i < n; i++) {
    cin >> c >> v;
    cars[i] = make_pair(v, c);
  }
  sort(cars.begin(), cars.end());
  long long c1 = 0, c2;
  vector<long long> baks(k + 2, 0);
  baks[k + 1] = s;
  for (long long i = 1; i <= k; i++) cin >> baks[i];
  sort(baks.begin(), baks.end());
  vector<long long> dist(k + 1);
  for (long long i = 1; i <= k + 1; i++) dist[i - 1] = baks[i] - baks[i - 1];
  sort(dist.begin(), dist.end());
  long long minV;
  if (t < s) {
    cout << -1;
    return 0;
  }
  long long leftV = 0;
  long long rightV = 2 * 10e9;
  while (rightV - leftV != 1) {
    long long mid = (rightV + leftV) / 2;
    long long time = 0;
    for (long long i = k; i >= 0; i--) {
      if (mid < dist[i]) {
        time = 1e10;
        break;
      }
      if (mid > 2 * dist[i])
        time += dist[i];
      else
        time += 3 * dist[i] - mid;
    }
    if (time > t)
      leftV = mid;
    else
      rightV = mid;
  }
  minV = rightV;
  long long ans = 10e9;
  for (long long i = 0; i < n; i++) {
    if (cars[i].first >= minV) {
      ans = min(ans, cars[i].second);
    }
  }
  if (ans == 1000000000)
    cout << -1;
  else
    cout << ans;
}
