#include <bits/stdc++.h>
using namespace std;
const long long int mod = 1000000007;
const long long int limit = 1000000;
void fc(long long int &x) {
  bool neg = false;
  register char c;
  x = 0;
  c = getchar();
  if (c == '-') {
    neg = true;
    c = getchar();
  }
  for (; (c > 47 && c < 58); c = getchar()) x = (x << 1) + (x << 3) + c - 48;
  if (neg) x *= -1;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n, q, t;
  long long int temp, temp1, temp2, temp3;
  long long int i, j, k, m;
  long long int cnt = 0;
  cin >> n >> m >> k;
  long long int arr[m];
  for (i = 0; i < m; i++) cin >> arr[i];
  temp = 0;
  temp1 = 0;
  for (i = 0; i < m; i++) {
    temp2 = i;
    temp1 = (arr[i] - temp2 - 1) / k + 1;
    temp3 = temp1;
    i++;
    temp3 = (arr[i] - temp2 - 1) / k + 1;
    while (temp1 == temp3 && i < m) {
      i++;
      temp3 = (arr[i] - temp2 - 1) / k + 1;
    }
    i--;
    cnt++;
  }
  cout << cnt << "\n";
}
