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 INF = 1000000000 + 1;
int n, k, s, t;
vector<pair<int, int> > cars;
vector<int> pos;
int calc(int c) {
  int ret = 0;
  for (int i = 0; i < (int)pos.size(); ++i) {
    if (c >= pos[i] * 2) {
      ret += pos[i];
    } else {
      ret += pos[i] * 2 - c + pos[i];
    }
  }
  return ret;
}
int main() {
  scanf("%d%d%d%d", &n, &k, &s, &t);
  for (int i = 0; i < n; ++i) {
    int c, v;
    scanf("%d%d", &c, &v);
    cars.push_back(make_pair(v, c));
  }
  for (int i = 0; i < k; ++i) {
    int g;
    scanf("%d", &g);
    pos.push_back(g);
  }
  pos.push_back(s);
  sort(pos.begin(), pos.end());
  for (int i = k; i > 0; --i) {
    pos[i] -= pos[i - 1];
  }
  sort(pos.begin(), pos.end());
  int l = *pos.rbegin(), maxc = 2 * l + 1, r = maxc;
  while (l < r) {
    int m = ((r - l) >> 1) + l;
    if (calc(m) <= t) {
      r = m;
    } else {
      l = m + 1;
    }
  }
  int minc = l;
  if (minc == maxc) {
    printf("-1\n");
  } else {
    int minv = INF;
    for (int i = 0; i < n; ++i) {
      if (cars[i].first >= minc) {
        minv = min(minv, cars[i].second);
      }
    }
    if (minv == INF) {
      printf("-1\n");
    } else {
      printf("%d\n", minv);
    }
  }
  return 0;
}
