#include <bits/stdc++.h>
using namespace std;
const int MAXM = 100000 + 5;
int64_t pp[MAXM];
int main() {
  ios::sync_with_stdio(false);
  int64_t n, m, k;
  cin >> n >> m >> k;
  for (auto i = 0; i < m; ++i) {
    cin >> pp[i];
  }
  int64_t ans = 0;
  int64_t discard = 0;
  int64_t cnt = 0;
  int64_t last_index = 0;
  int p_index = 0;
  while (p_index < m) {
    last_index = (cnt + 1) * k + discard;
    if (p_index < m && pp[p_index] <= last_index) {
      ans++;
      while (p_index < m && pp[p_index] <= last_index) {
        p_index++;
        discard++;
      }
    } else {
      auto diff = pp[p_index] - last_index;
      auto dcnt = diff / k + (diff % k > 0);
      cnt += dcnt;
    }
  }
  cout << ans << endl;
  return 0;
}
