#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  long long n;
  long long m;
  long long k;
  cin >> n >> m >> k;
  vector<long long> p(m);
  for (long long i = 0; i < m; ++i) {
    cin >> p[i];
  }
  long long i = 0;
  long long r = ((p[0] + k - 1) / k) * k;
  long long cur = 0;
  long long cnt = 0;
  long long ans = 0;
  while (i < m) {
    if (p[i] - cur > r && i < m) {
      r = ((p[i] - cur + k - 1) / k) * k;
    } else {
      cnt = 0;
      while (i < m && p[i] - cur <= r) {
        ++cnt;
        ++i;
      }
      ++ans;
      cur += cnt;
    }
  }
  cout << ans;
  return 0;
}
