#include <bits/stdc++.h> #define int long long using namespace std; int n,d,a[100005],b[100005]; int s,mx; signed main () { // freopen("c.in","r",stdin); // freopen("c.out","w",stdout); cin >> n >> d; for (int i = 1;i <= n;i++) { cin >> a[i]; if (a[i]) { b[i % d]++; s++; } } for (int i = 0;i < d;i++) { mx = max(mx,b[i]); } cout << (s - mx) << endl; return 0; }