#include <bits/stdc++.h>
using namespace std;
long long n, m, k, ans;
long long cl(long long a, long long b) {
  if (a % b == 0)
    return a / b;
  else
    return 1 + (a / b);
}
long long cur, deleted;
void comp(long long next, int index) {
  long long c = cur;
  long long nx = next;
  cur = cur - deleted;
  next = next - deleted;
  long long t1 = cl(cur, k);
  long long t2 = cl(next, k);
  if (t2 > t1) {
    ans++;
    cur = nx;
    deleted = index - 1;
  } else {
    cur = c;
  }
}
int main() {
  ans = 1;
  deleted = 0;
  cin >> n >> m >> k;
  long long next;
  cin >> cur;
  for (int i = 1; i < m; i++) {
    cin >> next;
    comp(next, i + 1);
  }
  cout << ans << endl;
}
