#include <bits/stdc++.h>
using namespace std;
int m, i;
long long n, k, a, b, c = 1, pages = -1, op;
int main() {
  scanf("%lld%d%lld", &n, &m, &k);
  for (i = 1; i <= m; i++) {
    scanf("%lld", &a);
    if (pages != (a - c) / k) {
      pages = (a - b - 1) / k;
      c = b + 1;
      op++;
    }
    b++;
  }
  printf("%d\n", op);
}
