#include <bits/stdc++.h>
using namespace std;
int main(int argc, char const *argv[]) {
  long long n, m, k, ans = 0, c = 1, val = 0;
  cin >> n >> m >> k;
  vector<long long> v(m);
  for (int i = 0; i < m; i++) cin >> v[i];
  for (int i = 0; i < m - 1; i++) {
    if (ceil((v[i] - val) / (k + 0.0)) == ceil((v[i + 1] - val) / (k + 0.0)))
      c += (c == 0) ? 2 : 1;
    else {
      ans++;
      val += max(c, 1LL);
      c = 0;
    }
  }
  if (c != 1 || ceil((v[m - 2] - val) / (k + 0.0)) !=
                    ceil((v[m - 1] - val) / (k + 0.0))) {
    ans++;
  }
  cout << ans << endl;
}
