#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m, k, a[100005], i, l, t, s, ans = 0, r, last;
  cin >> n >> k >> m;
  for (i = 1; i <= k; i++) cin >> a[i];
  s = 0;
  l = 1;
  while (l <= k) {
    ans++;
    last = l;
    t = a[l] - s;
    r = t / m * m + (t % m != 0) * m;
    while (a[l] - s <= r && l <= k) l++;
    s += l - last;
  }
  cout << ans;
  return 0;
}
