#include <bits/stdc++.h>
using namespace std;
signed main() {
  int64_t n, m, k;
  cin >> n >> m >> k;
  queue<int64_t> q;
  for (int64_t i = 0; i < m; i++) {
    int64_t p;
    cin >> p;
    p--;
    q.push(p);
  }
  int64_t ctr = 0;
  int64_t bef = 0;
  while (!q.empty()) {
    ctr++;
    int64_t curr = (q.front() - bef) / k;
    q.pop();
    int64_t cb = 1;
    while ((!q.empty()) && ((q.front() - bef) / k) == curr) {
      q.pop();
      cb++;
    }
    bef += cb;
  }
  cout << ctr << "\n";
}
