#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void sort(T& a) {
  sort(a.begin(), a.end());
}
template <class T>
inline void rsort(T& a) {
  sort(a.rbegin(), a.rend());
}
template <class T>
inline void reverse(T& a) {
  reverse(a.begin(), a.end());
}
template <class T>
inline int size(T& a) {
  int b = a.size();
  return b;
}
template <class T1, class T2>
inline void chkmin(T1& first, T2 second) {
  if (first > second) first = second;
}
template <class T1, class T2>
inline void chkmax(T1& first, T2 second) {
  if (first < second) first = second;
}
template <typename T>
inline ostream& operator<<(ostream& os, vector<T>& a) {
  for (int i = 0; i < size(a); i++) {
    os << a[i] << " ";
  }
  return os;
}
template <typename T>
inline istream& operator>>(istream& is, vector<T>& a) {
  for (int i = 0; i < size(a); i++) {
    is >> a[i];
  }
  return is;
}
template <typename T1, typename T2>
inline ostream& operator<<(ostream& os, pair<T1, T2>& a) {
  cout << "{" << a.first << ", " << a.second << "}";
  return os;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m, k;
  cin >> n >> m >> k;
  long long p;
  long long cnt = 0, l = -1, ans = 0;
  for (int i = 0; i < m; i++) {
    cin >> p;
    long long d = p - cnt;
    if ((d - 1) / k != l) {
      cnt = i;
      ans++;
      l = (p - cnt - 1) / k;
    }
  }
  cout << ans;
}
