#include <bits/stdc++.h>
using namespace std;
long long n, k;
int m, s;
long long p[100000 + 5], delta, ans;
int main() {
  scanf("%lld%d%lld", &n, &m, &k);
  for (int i = 1; i <= m; i++) scanf("%lld", &p[i]);
  s = 1;
  while (s <= m) {
    long long nb = (p[s] - delta - 1) / k;
    while ((p[s] - delta - 1) / k == nb && s <= m) s++;
    delta = s - 1;
    ans++;
  }
  printf("%lld", ans);
}
