#include <bits/stdc++.h>
#define ff first
#define ss second
#define endl '\n'
using namespace std;
const long long INF = (long long) 1e18;
const int mod = (int) 1e9+7;
const int MAXN = (int) 5e3+5;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
ll n, k;
int a[MAXN];
int b[MAXN];
map<int, int> blk;
int d(int ind, int mn){
if(ind == n) return 0;
int cur = a[ind];
if(cur < mn) return d(ind + 1, mn);
int sola = 0;
int ek = 0;
for(int i = ind + 1; i < n; i++){
if(a[i] < mn) sola++;
if(a[i] < cur && a[i] > mn){
ek++;
}
}
int cik = 0;
for(int i = 0; i < ind; i++){
if(a[i] >= cur){
cik++;
}
}
int curI = ind + sola - cik;
if(curI >= k*cur - k && curI < k*cur){
return d(ind + 1, mn);
}else{
ll ans1 = d(ind + 1, cur) + ek;
ll ans2 = d(ind + 1, mn) + 1;
//cout<<ind<<" "<<mn<<endl;
//cout<<ans1<<" "<<ans2<<endl;
return min(ans1, ans2);
}
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
#ifdef Local
freopen("../IO/int.txt","r",stdin);
freopen("../IO/out.txt","w",stdout);
#endif
cin>>n>>k;
for(int i = 0; i < n; i++){
cin>>a[i];
b[i] = a[i];
}
sort(b, b + n);
for(int i = 0; i < n; i++){
blk[b[i]] = i / k + 1;
}
for(int i = 0; i < n; i++){
a[i] = blk[a[i]];
}
cout<<d(0, 0);
#ifdef Local
cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
#endif
}
