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 = 200010;
const long long INF = 1e18;
long long c[maxn];
long long v[maxn];
long long g[maxn];
long long n, k, s, t;
bool judge(long long x) {
  long long Time = 0;
  for (int i = 0; i <= k; i++) {
    long long distance = g[i + 1] - g[i];
    if (distance > x) {
      return 0;
    }
    long long tmp = x - distance;
    tmp = min(distance, tmp);
    Time += tmp + (distance - tmp) * 2;
    if (Time > t) {
      return 0;
    }
  }
  if (Time > t) {
    return 0;
  } else {
    return 1;
  }
}
long long bs() {
  long long l = 1;
  long long r = 4e9 + 10;
  long long res = -1;
  while (l <= r) {
    long long mid = (l + r) >> 1;
    if (judge(mid)) {
      res = mid;
      r = mid - 1;
    } else {
      l = mid + 1;
    }
  }
  return res;
}
int main() {
  cin >> n >> k >> s >> t;
  for (int i = 1; i <= n; i++) {
    scanf("%I64d %I64d", &c[i], &v[i]);
  }
  for (int i = 1; i <= k; i++) {
    scanf("%I64d", &g[i]);
  }
  sort(g + 1, g + k + 1);
  g[0] = 0;
  g[k + 1] = s;
  long long MIN = bs();
  long long res = INF;
  for (int i = 1; i <= n; i++) {
    if (v[i] >= MIN) {
      res = min(res, c[i]);
    }
  }
  if (res == INF) {
    cout << -1 << endl;
  } else {
    cout << res << endl;
  }
  return 0;
}
