#include <bits/stdc++.h>
using namespace std;
long long int power(long long int a, long long int b) {
  long long int res = 1;
  a %= 1000000007;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % 1000000007;
    a = a * a % 1000000007;
  }
  return res;
}
long long int modInverse(long long int a) { return power(a, 1000000007 - 2); }
const int N = 500023;
bool vis[N];
vector<int> adj[N];
void solve() {
  long long int n, m, k;
  cin >> n >> m >> k;
  vector<long long int> v(m);
  for (long long int i = 0; i < m; i++) cin >> v[i];
  long long int deleted = 0;
  long long int count = 0;
  long long int now = 0;
  while (now < m) {
    long long int r = ((v[now] - deleted - 1) / k + 1) * k + deleted;
    while (now < m && v[now] <= r) {
      deleted++;
      now++;
    }
    count++;
  }
  cout << count << endl;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int T = 1;
  int t = 0;
  while (t++ < T) {
    solve();
  }
  cerr << "Time : " << 1000 * ((double)clock()) / (double)CLOCKS_PER_SEC
       << "ms\n";
}
