#include <bits/stdc++.h>
using namespace std;
const long long N = 2e5 + 5, inf = 1e18;
long long n, m, k, ans, a[N], ps;
deque<long long> vec;
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m >> k;
  for (long long i = 1; i <= m; i++) {
    cin >> a[i];
    a[i]--;
    vec.push_back(a[i]);
  }
  while (vec.size()) {
    ans++;
    long long t = 0;
    long long id = (vec.front() - ps) / k;
    while (vec.size() && (vec.front() - ps) / k == id) {
      t++;
      vec.pop_front();
    }
    ps += t;
  }
  cout << ans;
  return 0;
}
