#include <bits/stdc++.h>
using namespace std;
long long a[100010];
int main() {
  long long n, m, k;
  while (cin >> n >> m >> k) {
    long long ans = 0;
    for (int i = 0; i < m; ++i) {
      scanf("%lld", a + i);
    }
    long long tmp1 = 0, p = 0;
    while (p < m) {
      tmp1 = p;
      long long tmp = (a[p] - tmp1 + k - 1) / k;
      for (p; (a[p] - tmp1 + k - 1) / k == tmp; ++p)
        ;
      ++ans;
    }
    cout << ans << endl;
  }
  return 0;
}
