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2 3 4 5 6
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1
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 1000000000000000000 2 1
1 1000000000000000000
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 101 55 10
1 3 5 7 8 9 10 16 18 21 22 23 24 25 27 30 32 35 36 37 38 39 40 43 45 47 49 50 51 52 54 57 59 61 64 66 67 68 69 70 71 72 73 80 83 86 87 88 89 90 91 92 96 97 98
 1000000000000000000 5 1000
1 1000000000 1000000000000 1000000000000000 1000000000000001
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 107 20 13
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 1000000000 2 1000000000
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102306300054748096 267367244641009859
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2
 1
 10
 2
 32
 15
 4
 1
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 35
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 20

#include <bits/stdc++.h>
using namespace std;
const int MX = 1e5 + 5;
long long mx[MX << 2], lz[MX << 2], a[MX];
void PushUP(int rt) { mx[rt] = max(mx[rt << 1], mx[rt << 1 | 1]); }
void PushDown(int rt) {
  if (lz[rt]) {
    mx[rt << 1] += lz[rt], mx[rt << 1 | 1] += lz[rt];
    lz[rt << 1] += lz[rt], lz[rt << 1 | 1] += lz[rt];
    lz[rt] = 0;
  }
}
void build(int l, int r, int rt) {
  if (l == r) {
    scanf("%d", &mx[rt]);
    mx[rt]--;
    a[l] = mx[rt];
    return;
  }
  int m = (l + r) >> 1;
  build(l, m, rt << 1), build(m + 1, r, rt << 1 | 1);
  PushUP(rt);
}
void update(int L, int R, int x, int l, int r, int rt) {
  if (L <= l && R >= r) {
    mx[rt] -= x;
    lz[rt] -= x;
    return;
  }
  PushDown(rt);
  int m = (l + r) >> 1;
  if (L <= m) update(L, R, x, l, m, rt << 1);
  if (R > m) update(L, R, x, m + 1, r, rt << 1 | 1);
  PushUP(rt);
}
int query(int L, int R, long long x, int l, int r, int rt) {
  if (l == r) return l;
  PushDown(rt);
  int m = (l + r) >> 1;
  if (L <= m && R > m) {
    if (mx[rt << 1] < x) return query(L, R, x, m + 1, r, rt << 1 | 1);
    return query(L, R, x, l, m, rt << 1);
  }
  if (L <= m) return query(L, R, x, l, m, rt << 1);
  return query(L, R, x, m + 1, r, rt << 1 | 1);
}
long long find(int p, int l, int r, int rt) {
  if (l == r) return mx[rt];
  PushDown(rt);
  int m = (l + r) >> 1;
  if (p <= m) return find(p, l, m, rt << 1);
  return find(p, m + 1, r, rt << 1 | 1);
}
int main() {
  long long n, k;
  int m;
  cin >> n >> m >> k;
  build(1, m, 1);
  int cnt = 0, idx = 1;
  while (idx <= n) {
    cnt++;
    long long pag = find(idx, 1, m, 1) / k;
    int r = query(idx, m, (pag + 1) * k - 1, 1, m, 1);
    if (r == m) break;
    update(idx, m, r - idx + 1, 1, m, 1);
    idx = r + 1;
  }
  printf("%d\n", cnt);
  return 0;
}
