#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 200020;
ll t[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ll n, m, a, d;
  cin >> n >> m >> a >> d;
  for (int i = 1; i <= m; ++i) cin >> t[i];
  t[0] = a;
  t[++m] = n * a;
  sort(t, t + m);
  ll res = 0, lt = -1;
  for (int i = 0; i < m; ++i) {
    if (lt < t[i]) {
      lt = t[i] + d;
      ++res;
    }
    ll st = max(lt / a, 1ll), ed = min(n, t[i + 1] / a);
    if (st * a <= lt) ++st;
    if (st > ed) continue;
    if (d < a) {
      lt = a * ed + d;
      res += ed - st + 1;
    } else {
      ll cc = d / a + 1, tc = ed - st + 1;
      res += tc / cc;
      tc %= cc;
      if (tc) {
        ++res;
        lt = (ed - tc + 1) * a + d;
      } else {
        lt = a * ed + d % a;
      }
    }
  }
  cout << res << '\n';
  return 0;
}
