#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
ll a[100005];
int main() {
  ios_base::sync_with_stdio(false), cin.tie(0);
  cout.precision(10);
  cout << fixed;
  ll n, m, k;
  cin >> n >> m >> k;
  ll delt = 0;
  for (int i = 1; i <= m; i++) {
    cin >> a[i];
  }
  ll cnt = 0;
  while (delt < m) {
    ll pg = (a[delt + 1] - delt + k - 1) / k;
    ll d = delt + 1;
    while (d < m && (a[d + 1] - delt + k - 1) / k == pg) d++;
    cnt++;
    delt = d;
  }
  cout << cnt << "\n";
  return 0;
}
