#include <bits/stdc++.h>
using namespace std;
signed main() {
  long long int n, i, m, k, x, pc = 0, c = 0;
  cin >> n >> m >> k;
  long long int p, f;
  queue<long long int> q;
  for (i = 0; i < m; i++) {
    cin >> x;
    q.push(x - 1);
  }
  x = 0;
  while (!q.empty()) {
    f = q.front();
    p = (f - c) / k;
    while (!q.empty() && ((q.front() - c) / k) == p) {
      pc++;
      q.pop();
    }
    c = pc;
    x++;
  }
  cout << x;
}
