#include <bits/stdc++.h>
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
const int inf = 0x3f3f3f3f, Inf = 0x7fffffff;
const long long INF = 0x7ffffffffffffff;
unsigned int seed = 19260817;
__inline__ __attribute__((always_inline)) unsigned int Rand() {
  return seed = seed * 998244353u + 1000000007u;
}
template <typename _Tp>
_Tp gcd(const _Tp &a, const _Tp &b) {
  return (!b) ? a : gcd(b, a % b);
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) _Tp abs(const _Tp &a) {
  return a > 0 ? a : -a;
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) _Tp max(const _Tp &a, const _Tp &b) {
  return a < b ? b : a;
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) _Tp min(const _Tp &a, const _Tp &b) {
  return a < b ? a : b;
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) void chmax(_Tp &a, const _Tp &b) {
  (a < b) && (a = b);
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) void chmin(_Tp &a, const _Tp &b) {
  (a > b) && (a = b);
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) bool ismax(_Tp &a, const _Tp &b) {
  return a > b ? 1 : a = b, 0;
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) bool ismin(_Tp &a, const _Tp &b) {
  return a < b ? 1 : a = b, 0;
}
template <typename _Tp>
__inline__ __attribute__((always_inline)) void read(_Tp &x) {
  register char ch(getchar());
  bool f(false);
  while (ch < 48 || ch > 57) f |= ch == 45, ch = getchar();
  x = ch & 15, ch = getchar();
  while (ch >= 48 && ch <= 57)
    x = (((x << 2) + x) << 1) + (ch & 15), ch = getchar();
  if (f) x = -x;
}
template <typename _Tp, typename... Args>
__inline__ __attribute__((always_inline)) void read(_Tp &t, Args &...args) {
  read(t);
  read(args...);
}
__inline__ __attribute__((always_inline)) int read_str(char *s) {
  register char ch(getchar());
  while (ch < 65 || ch > 122 || (ch > 90 && ch < 97)) ch = getchar();
  register char *tar = s;
  *tar = ch, ch = getchar();
  while ((ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122))
    *(++tar) = ch, ch = getchar();
  return tar - s + 1;
}
const int N = 100005;
long long a[N];
int main() {
  long long n;
  long long m, k;
  read(n, m, k);
  for (int i = 1; i <= m; ++i) {
    read(a[i]);
  }
  long long pos = 0, ans = 0;
  long long sum = 0;
  while (pos != m) {
    ++pos, ++ans;
    long long r = ((a[pos] - sum + k - 1) / k) * k;
    while (pos < m && a[pos + 1] <= r + sum) {
      ++pos;
    }
    sum = pos;
  }
  printf("%lld\n", ans);
  return 0;
}
