#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, k;
  int m;
  cin >> n >> m >> k;
  int act = 1, ant = 1;
  long long l = 1, r = k, ans = 0, q = 0, num;
  while (act <= m) {
    cin >> num;
    if (!(num - q >= l and num - q <= r)) {
      q += act - ant;
      if (act != 1) ans++;
      ant = act;
      r = (num - q + k - 1) / k * k;
      l = r - k + 1;
    }
    act++;
  }
  cout << ans + 1 << endl;
  return 0;
}
