#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
long long n, m, a, d, ans = 0, t[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> m >> a >> d;
  long long e, s, len;
  for (int i = 0; i < m; ++i) cin >> t[i];
  sort(t, t + m);
  long long ls = 0, df = d / a + 1;
  for (int i = 0; i < m; ++i) {
    if (t[i] <= ls) continue;
    e = ((t[i] / a < n) ? (t[i] / a) : (n));
    ;
    s = ((ls / a < n) ? (ls / a) : (n));
    ;
    len = e - s;
    ans += len / df + (len % df != 0);
    if (len != 0) {
      ls = a * (e + 1) + d;
      if (len % df == 0)
        ls -= a * df;
      else
        ls -= a * (len % df);
    }
    if (t[i] > ls) {
      ls = t[i] + d;
      ans++;
    }
  }
  e = n;
  s = ((ls / a < n) ? (ls / a) : (n));
  ;
  len = e - s;
  ans += len / df + (len % df != 0);
  cout << ans << endl;
  return 0;
}
