This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
#include <set>
#include <stack>
#include <map>
#include <unordered_map>
#include <iomanip>
#include <cmath>
#include <queue>
#include <bitset>
#include <numeric>
#include <array>
#include <cstring>
#include <random>
#include <chrono>
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define make_unique(x) sort(all((x))); (x).resize(unique(all((x))) - (x).begin())
typedef long long ll;
typedef long double ld;
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
// using namespace __gnu_pbds;
// template<class T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2e5 + 42;
int fw[N];
void upd(int k, int x) {
  for(; k < N; k += (k & -k)) fw[k] = max(fw[k], x);
}
int get(int k) {
  int res = 0;
  for(; k > 0; k -= (k & -k)) res = max(res, fw[k]);
  return res;
}
int n, m;
int main() {
  ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  cin >> n >> m;
  vector<int> a;
  for(int i = 1; i <= n; i++) {
    int x; cin >> x;
    if(i * m - x >= 0) a.pb(i * m - x);
  }
  auto p = a;
  make_unique(p);
  map<int, int> nind;
  for(int i = 0; i < p.size(); i++) nind[p[i]] = i + 1;
  for(auto& x : a) x = nind[x];
  for(auto& x : a) {
    upd(x, get(x) + 1);
  }
  cout << n - get(N - 1);
  return 0;
}
/*
*/
Compilation message (stderr)
triusis.cpp:3: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    3 | #pragma GCC optimization ("unroll-loops")
      | 
triusis.cpp: In function 'int main()':
triusis.cpp:67:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |   for(int i = 0; i < p.size(); i++) nind[p[i]] = i + 1;
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