#include <bits/stdc++.h>
using namespace std;
int mod(int n) {
  if (n >= 0)
    return n;
  else
    return (-n);
}
void solve() {
  long long int n;
  long long int m, k;
  cin >> n >> m >> k;
  vector<long long int> v(m);
  for (int i = 0; i < m; i++) cin >> v[i];
  long long int i = 0, p = 0, co = 0, ans = 0;
  while (i != m) {
    long long int c1 = 0;
    long long int d = (v[i] - p - 1) / k;
    long long int l = d * k + 1;
    long long int r = (d + 1) * k;
    while ((v[i] - p <= r) && (i < m)) {
      i++;
      c1++;
    }
    p = i;
    if (c1 != 0) ans++;
  }
  cout << ans;
}
int main() {
  std::ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int t;
  t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
