#include <bits/stdc++.h>
using namespace std;
const long long N = 100050;
long long in[N];
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  long long n, m, a, d, i, j;
  cin >> n >> m >> a >> d;
  for (i = 1; i <= m; i++) cin >> in[i];
  long long c = d / a + 1;
  long long ans = 0, p1 = 0, p2 = 0;
  while (p1 != n || p2 != m) {
    if (p1 != n && (p2 == m || (p1 + 1) * a < in[p2 + 1])) {
      long long x = min(n + 1, (in[p2 + 1] + a - 1) / a) - (p1 + 1);
      if (p2 == m) x = n - p1;
      long long c2 = (x + c - 1) / c;
      long long s = (p1 + 1) * a, e = s + c * (c2 - 1) * a + d;
      p2 = lower_bound(in + 1, in + m + 1, e + 1) - (in + 1);
      p1 = min(n, e / a);
      ans += c2;
    } else {
      ans++;
      long long s = in[p2 + 1], e = s + d;
      p2 = lower_bound(in + 1, in + m + 1, e + 1) - (in + 1);
      p1 = min(n, e / a);
    }
  }
  cout << ans << endl;
  return 0;
}
