#include <bits/stdc++.h>
using namespace std;
long long n, m, k, sum, num, ans;
long long a[200005];
int main() {
  cin >> n >> m >> k;
  for (int i = 1; i <= m; i++) cin >> a[i];
  sort(a + 1, a + m + 1);
  sum = 0, num = 1, ans = 1;
  for (int i = 2; i <= m; i++) {
    if ((a[i] - 1 - sum) / k != (a[i - 1] - 1 - sum) / k) {
      ans++;
      sum += num;
      num = 1;
    } else
      num++;
  }
  cout << ans;
  return 0;
}
